Hydrodynamic instability growth at the deuterium-tritium(DT)fuel-ablator interface plays a critical role in determining the performance of inertial confinement fusion implosions.During the late stages of implosion,ins...Hydrodynamic instability growth at the deuterium-tritium(DT)fuel-ablator interface plays a critical role in determining the performance of inertial confinement fusion implosions.During the late stages of implosion,insufficient doping of the ablator material can result in highenergy X-ray preheat,which may trigger the development of a classical-like Rayleigh-Taylor instability(RTI)at the fuel-ablator interface.In implosion experiments at the Shenguang 100 kJ-level laser facility,the primary source of perturbation is the roughness of the inner DT ice interface.In this study,we propose an analytical model to describe the feed-out process of the initial roughness of the inner DT ice interface.The perturbation amplitude derived from this model serves as the initial seed for the late-time RTI during the acceleration phase.Our findings confirm the presence of classical-like RTI at the fuel-ablator interface.Numerical simulations conducted using a radiation hydrodynamic code validate the proposed analytical model and demonstrate the existence of a peak mode number in both the feed-out process and the classical-like RTI.It provides an alternative bridge between the current target fabrication limitations and the unexpected implosion performance.展开更多
We present and explore a new shock-capturing particle hydrodynamics approach.Our starting point is a commonly used discretization of smoothed particle hydrodynamics.We enhance this discretization with Roe’s approx-im...We present and explore a new shock-capturing particle hydrodynamics approach.Our starting point is a commonly used discretization of smoothed particle hydrodynamics.We enhance this discretization with Roe’s approx-imate Riemann solver,we identify its dissipative terms,and in these terms,we use slope-limited linear reconstruction.All gradients needed for our method are calculated with linearly reproducing kernels that are constructed to enforce the two lowest-order consistency relations.We scrutinize our reproducing kernel implementation carefully on a“glass-like”particle distribution,and we find that constant and linear functions are recovered to machine precision.We probe our method in a series of challenging 3D benchmark problems ranging from shocks over instabilities to Schulz-Rinne-type vorticity-creating shocks.All of our simulations show excellent agreement with analytic/reference solutions.展开更多
Ocean energy has progressively gained considerable interest due to its sufficient potential to meet the world’s energy demand,and the blade is the core component in electricity generation from the ocean current.Howev...Ocean energy has progressively gained considerable interest due to its sufficient potential to meet the world’s energy demand,and the blade is the core component in electricity generation from the ocean current.However,the widened hydraulic excitation frequency may satisfy the blade resonance due to the time variation in the velocity and angle of attack of the ocean current,even resulting in blade fatigue and destructively interfering with grid stability.A key parameter that determines the resonance amplitude of the blade is the hydrodynamic damping ratio(HDR).However,HDR is difficult to obtain due to the complex fluid-structure interaction(FSI).Therefore,a literature review was conducted on the hydrodynamic damping characteristics of blade-like structures.The experimental and simulation methods used to identify and obtain the HDR quantitatively were described,placing emphasis on the experimental processes and simulation setups.Moreover,the accuracy and efficiency of different simulation methods were compared,and the modal work approach was recommended.The effects of key typical parameters,including flow velocity,angle of attack,gap,rotational speed,and cavitation,on the HDR were then summarized,and the suggestions on operating conditions were presented from the perspective of increasing the HDR.Subsequently,considering multiple flow parameters,several theoretical derivations and semi-empirical prediction formulas for HDR were introduced,and the accuracy and application were discussed.Based on the shortcomings of the existing research,the direction of future research was finally determined.The current work offers a clear understanding of the HDR of blade-like structures,which could improve the evaluation accuracy of flow-induced vibration in the design stage.展开更多
In this work,we present a parallel implementation of radiation hydrodynamics coupled with particle transport,utilizing software infrastructure JASMIN(J Adaptive Structured Meshes applications INfrastructure)which enca...In this work,we present a parallel implementation of radiation hydrodynamics coupled with particle transport,utilizing software infrastructure JASMIN(J Adaptive Structured Meshes applications INfrastructure)which encapsulates high-performance technology for the numerical simulation of complex applications.Two serial codes,radiation hydrodynamics RH2D and particle transport Sn2D,have been integrated into RHSn2D on JASMIN infrastructure,which can efficiently use thousands of processors to simulate the complex multi-physics phenomena.Moreover,the non-conforming processors strategy has ensured RHSn2D against the serious load imbalance between radiation hydrodynamics and particle transport for large scale parallel simulations.Numerical results show that RHSn2D achieves a parallel efficiency of 17.1%using 90720 cells on 8192 processors compared with 256 processors in the same problem.展开更多
Mangrove ecosystems along Vietnam’s coastline face significant degradation due to human activities,despite their crucial role in coastal protection against natural hazards.This study aims to assess the spatial and te...Mangrove ecosystems along Vietnam’s coastline face significant degradation due to human activities,despite their crucial role in coastal protection against natural hazards.This study aims to assess the spatial and temporal changes in mangrove coverage along Vietnam’s southern coast by integrating remote sensing techniques with hydrodynamic model simulations.The research methodology combines the Collect Earth tool analysis of Spot-4 and Planet satellite imagery(2000–2020)with Mike 21-HD two-dimensional(2D)hydrodynamic modeling to evaluate mangrove coverage changes by simulating shoreline erosion.Results analysis reveals that a significant increase of 109.83 ha in mangrove area within Vinh Chau Town of Soc Trang Province during the period 2010–2020,predominantly in the eastern region.Hydrodynamic simulations demonstrate that the coastal zone is primarily influenced by the interaction of nearshore currents,East Sea tides,and seasonal monsoon wave patterns.The model results effectively capture the complex interactions between these hydrodynamic factors and mangrove distribution.These findings not only validate the effectiveness of combining remote sensing and hydrodynamic modeling for mangrove assessment but also provide crucial insights for sustainable coastal ecosystem management.The study’s integrated approach offers a robust framework for monitoring mangrove dynamics and developing evidence-based conservation strategies,highlighting the importance of maintaining these vital ecosystems for coastal protection.展开更多
The synergetic technology of hydrodynamic cavitation(HC)and peroxydisulfate(PDS)has been adopted for the treatment of organic pollutants,while the rationale behind the thermal-activation of PDS in this process remains...The synergetic technology of hydrodynamic cavitation(HC)and peroxydisulfate(PDS)has been adopted for the treatment of organic pollutants,while the rationale behind the thermal-activation of PDS in this process remains lacking.This paper presented investigation on the degradation of tetracycline under two types of operating conditions,including“internal reaction conditions”(pH value and TC/PDS molar ratio)and“external physical conditions”(hole shape,solution temperature and inlet pressure).Special emphasis was paid on the analysis of thermal effects through a robust modeling approach.The results showed that a synergy index of 6.26 and a degradation rate of 56.71%could be obtained by the HC-PDS process,respectively,when the reaction conditions were optimized.Quenching experiment revealed that·OH and·SO_(4)^(-)were the predominant free radicals and their contribution to the degradation was 75.4%and 24.6%respectively,since a part of·SO_(4)^(-)was transformed into·OH in the solution.The thermal activation of PDS mainly occurred near the hole where the fitting temperature was around 340 K,while·OH was generated in the bubble collapse region downstream the hole,where the temperature was much higher and favorable for the cleavage of water molecular.The average temperature under different external physical conditions was in good consistence with the degradation rates.This research developed a useful method to effectively evaluate the activation extent of PDS by HC and could provide reliable guidance for further development of cavitational reactors to treat organic pollutants based on this hybrid approach.展开更多
Particle transport is a fundamental aspect of various systems,from artificial to biological.A common assumption is that particle motion follows Markovian(memoryless)processes in the absence of interaction between part...Particle transport is a fundamental aspect of various systems,from artificial to biological.A common assumption is that particle motion follows Markovian(memoryless)processes in the absence of interaction between particles.However,hydrodynamic memory and the interaction between particles are ubiquitous,leaving many fundamental questions unanswered regarding transport of interacting particles involving hydrodynamic drag in corrugated channels,as described by the fractional Langevin equation.This study examines the hydrodynamic transport of interacting non-Brownian particles moving within a corrugated channel.We propose a method that relies on factors such as temperature,the driving force to alternate between no transport and finite net transport.Of importance is to note that the absence of transport results from the clogging,while the transport consists of collective motion and independent motion.The transport systems investigated in this work suggest the potential for sensor functionality within the system.Our findings may prove valuable for exploring the transport with hydrodynamic memory in various fields,including biology,physics,and chemistry.展开更多
Rip currents are a significant threat to swimmers worldwide,responsible for numerous drowning incidents each year.In Vietnam,Bai Dai Beach in Cam Ranh Bay,Khanh Hoa Province,has experienced an increase in drowning eve...Rip currents are a significant threat to swimmers worldwide,responsible for numerous drowning incidents each year.In Vietnam,Bai Dai Beach in Cam Ranh Bay,Khanh Hoa Province,has experienced an increase in drowning events due to rip currents in recent years.To address this issue,a comprehensive study was conducted based on developing a depth-averaged 2D hydrodynamic model to simulate rip currents in the Bai Dai-Cam Ranh coast.The HYDIST-2D numerical model was applied to simulate the rip current evolution in space and time for the study area.The results showed that the HYDIST-2D numerical model can accurately predict the location,magnitude,and microstructure of rip currents,including rip current speed,width,and length.The simulation results revealed that the rip current speed is greater during the low tide phase,with an average speed of 0.5 m s^(-1),while during high tide,the rip current speed is lower,around 0.1–0.8 m s^(-1).The width and length of the rip current also vary with the tide phase,with a wider and longer rip current observed during the low tide phase.The results also showed that the rip current speed and microstructure are influenced by the wave features,tide current,and bathymetry of the study area.The present study provides valuable insights into the dynamics of rip currents in the Bai Dai-Cam Ranh coast.The findings can be used to support the management of bathing activities and provide early warnings for potential risks associated with rip currents.展开更多
Floating breakwaters(FBs)are commonly employed for the protection of coastal installations.In this work,a convextype floating breakwater(FB)is proposed,and its hydrodynamic characteristics are studied through systemat...Floating breakwaters(FBs)are commonly employed for the protection of coastal installations.In this work,a convextype floating breakwater(FB)is proposed,and its hydrodynamic characteristics are studied through systematic laboratory experiments.Two different deck widths and two different mooring systems are set in the experiment.The transmission coefficients,reflection coefficients,motion responses and mooring forces of convex-type FBs are obtained in experiments.The influences of the deck width and mooring system on the hydrodynamic characteristics of the proposed FB are analyzed and compared.The experimental results show that the reflection coefficient and mooring force of the convex-type FB with a cross-mooring system are significantly larger than those of the convextype FB with a parallel-mooring system.A convex-type FB with a larger deck width has a higher reflection coefficient.The convex-type FBs with cross-and parallel-mooring systems have similar surge and heave motions,but the cross-mooring results in small roll motion.In addition,reliable prediction formulas for the transmission coefficient of convex-type FBs with different mooring systems have been developed,which are important for engineering design.展开更多
The growth of computing power in data centers(DCs)leads to an increase in energy consumption and noise pollution of air cooling systems.Chip-level cooling with high-efficiency coolant is one of the promising methods t...The growth of computing power in data centers(DCs)leads to an increase in energy consumption and noise pollution of air cooling systems.Chip-level cooling with high-efficiency coolant is one of the promising methods to address the cooling challenge for high-power devices in DCs.Hybrid nanofluid(HNF)has the advantages of high thermal conductivity and good rheological properties.This study summarizes the numerical investigations of HNFs in mini/micro heat sinks,including the numerical methods,hydrothermal characteristics,and enhanced heat transfer technologies.The innovations of this paper include:(1)the characteristics,applicable conditions,and scenarios of each theoretical method and numerical method are clarified;(2)the molecular dynamics(MD)simulation can reveal the synergy effect,micro motion,and agglomeration morphology of different nanoparticles.Machine learning(ML)presents a feasiblemethod for parameter prediction,which provides the opportunity for the intelligent regulation of the thermal performance of HNFs;(3)the HNFs flowboiling and the synergy of passive and active technologies may further improve the overall efficiency of liquid cooling systems in DCs.This review provides valuable insights and references for exploring the multi-phase flow and heat transport mechanisms of HNFs,and promoting the practical application of HNFs in chip-level liquid cooling in DCs.展开更多
Pulsating flow is a common condition for under water manipulators in Bohai Bay.This study aimed to investigate the effects of pulsation frequency and amplitude on the hydrodynamic characteristics of an underwater mani...Pulsating flow is a common condition for under water manipulators in Bohai Bay.This study aimed to investigate the effects of pulsation frequency and amplitude on the hydrodynamic characteristics of an underwater manipulator with different postures using the user-defined function (UDF) method. The lift coefficient (C_(L)), drag coefficient (C_(D)), and vortex shedding of the underwater manipulator in single-and dualarm forms were obtained. Results indicated that the maximum increase in the lift and drag coefficients subjected to the pulsation parameters was 24.45%and 28%, respectively, when the fluid flowed past a single arm. Compared with the single arm, the lift and drag coefficients of the arms were higher than those of the single arm when arm 2 was located upstream. Additionally, the pulsation frequency had no obvious effect on the manipulator, but the C_(L) and C_(D) of arm 2 showed an obvious increasing trend with an increase in pulsation amplitude. Meanwhile, when arm 2 was located downstream, the C_(L) and C_(D) of arm 2 were reduced by 16.38%and 1.15%, respectively, with an increase in the pulse frequency,and the maximum increase in the lift and dragcoefficients was 33.33%and 16.78%,respectively,with increasing pulsation amplitude.Moreover, the downstream wake morphology changed significantly, and a combined vortex phenomenon appeared. Finally, a theoretical basis for examining the hydrodynamic characteristics of marine engineering equipment was established to aid future marine resource exploitation.展开更多
Two asymmetric types of floating breakwaters integrated with a wave energy converter(WEC-FBs),a floating square box with a triangle(trapezoidal type)or a wave baffle(L type)attached to its rear side,have been proposed...Two asymmetric types of floating breakwaters integrated with a wave energy converter(WEC-FBs),a floating square box with a triangle(trapezoidal type)or a wave baffle(L type)attached to its rear side,have been proposed.In this research,the hydrodynamic performance,including capture width ratio(CWR),wave transmission coefficient,heave motion,and force coefficient,were studied and compared between the two types.A numerical simulation model based on the Navier-Stokes equation was employed.The effects of power take-off(PTO)damping coefficient,wave periods,and draft/displacement on the hydrodynamic performance of the two structure shapes were simulated and investigated.The results reveal that the L type performs better in shorter wave periods,and the trapezoidal type exhibits a higher CWR in intermediate wave periods.This study offers knowledge of the design and protection of the two WEC-FB types.展开更多
This study experimentally investigates the hydrodynamic characteristics,geometric configurations,fluttering motions of the codend,and the instantaneous flow fields inside and around the codend,with and without a liner...This study experimentally investigates the hydrodynamic characteristics,geometric configurations,fluttering motions of the codend,and the instantaneous flow fields inside and around the codend,with and without a liner,under varying catch sizes and inflow velocities.A proper orthogonal decomposition method is employed to extract phase-averaged mean properties of unsteady turbulent flows from flow measurement data obtained using an electromagnetic current velocity meter inside and around the codend.The results reveal that as catch size increases,the drag force,codend motion,Reynolds number,and codend volume increase while the drag coefficient decreases.Owing to the codend shape and pronounced motion,a complex fluid–structure interaction occurs,demonstrating a strong correlation between drag force and codend volume.The oscillation amplitudes of the hydrodynamic forces and codend motions increase with increasing catch size,and their oscillations mainly involve low-frequency activity.A significant reduction in the flow field occurs inside and around the unlined codend without a catch.The flow field is 5.81%,14.39%,and 27.01%lower than the unlined codend with a catch,the codend with a liner but without a catch,and the codend with both a liner and a catch,respectively.Fourier analysis reveals that the codend motions and hydrodynamic forces are mainly characterized by low-frequency activity and are synchronized with the unsteady turbulent flow street.Furthermore,the proper orthogonal decomposition results reveal the development of unsteady turbulent flow inside and around the codend,driven by flow passage blockage caused by the presence of the liner,intense codend motions,and the catch.Understanding the hydrodynamic characteristics and flow instabilities inside and around the codend,particularly those associated with its fluttering motions,is crucial for optimizing trawl design and improving trawl selectivity.展开更多
To propel the application of a bottom-hinged flap breakwater in real sea conditions,a two-dimensional computational fluid dynamics numerical model was conducted to investigate the pitching motion response and wave att...To propel the application of a bottom-hinged flap breakwater in real sea conditions,a two-dimensional computational fluid dynamics numerical model was conducted to investigate the pitching motion response and wave attenuation in random waves.First,the flow velocity distribution characteristic of the pitching flap at typical times was summarized.Then,the effects of random wave and flap parameters on the flap’s significant pitching angle amplitude θ_(s) and hydrodynamic coefficients were investigated.The results reveal that θ_(s) and wave reflection coefficient K_(r) values increase with increasing significant wave height Hs,random wave steepnessλs,and flap relative height.As Hs andλs increase,the wave transmission coefficient K_(t) increases while the wave dissipation coefficient K_(d) decreases.Additionally,K_(t) decreases with increasing flap relative height.With increasing equivalent damping coefficient ratio,θ_(s) and K_(t) decrease,while K_(r) and K_(d) increase.The relationships betweenλs and flap relative height on the one hand andθ_(s),K_(r),K_(t),and K_(d) in random waves on the other hand are compared to those in regular waves.Based on the equal incident wave energy and the equal incident wave energy flux,the pitching flap performs better in the wave attenuation capability under random waves than in regular waves.Finally,the dimensionless parameters with respect to random wave and flap were used to derive the K_(r) and K_(t) for-mulae,which were validated with the related data.展开更多
Past investigations of the hydrodynamic forces on vertical columns have generally been based on rigid structure assumptions.The effects of structural flexibility and geometry characteristics on the hydrodynamic force ...Past investigations of the hydrodynamic forces on vertical columns have generally been based on rigid structure assumptions.The effects of structural flexibility and geometry characteristics on the hydrodynamic force distribution are not well understood.In this study,fluid-structure interaction models are developed for numerical analyses.This modeling technique is verified with an experimental test in the literature using both circular and rectangular cross-sections.A series of material elasticities that present structural properties ranging from rigid to flexible is then used to conduct analyses.This finding indicates that an increase in structural flexibility can decrease the impact force to some extent,but this effect is limited.A concrete bridge pier with fluid flow impact can be considered rigid when it is fixed at the bottom.After that,the effects of the initial downstream water height and the width of water tank on the hydrodynamic force are thoroughly investigated.The results demonstrate that the increase in the downstream water height with a constant upstream water height corresponds to a decreased force.Moreover,the vertical column results in a blockage effect on the fluid flow.The greater the blockage effect,the higher the hydrodynamic force.The blockage effect from the vertical column can be neglected when the tank width is greater than eight times the structural cross-section diameter.展开更多
demand for faster vessels continues to grow,various high speed vessels have been designed and constructed for military,recreational,and passenger use.Planing vessels,specifically engineered for high-speed travel,requi...demand for faster vessels continues to grow,various high speed vessels have been designed and constructed for military,recreational,and passenger use.Planing vessels,specifically engineered for high-speed travel,require optimization to improve their hydrodynamic performance and stability during design.Reducing resistance and improving longitudinal stability are key challenges in the design of high-speed vessels.Various methods are employed to overcome these challenges,with the use of a transverse step being one of the most common approaches.This study explores the effect of changing the angle of the aft-wise step and incorporates these changes into existing analytical formulas,resulting in new formulas specifically for high-speed vessels equipped with aft-wise steps.This research investigates how the angle of the transverse step affects the hydrodynamic performance and longitudinal stability of high-speed vessels.Based on the results,analytical formulas have been developed to calculate the wetted surface parameters of vessels equipped with an aft-wise transverse step.The study used experimental methods to analyze the vessel's behavior with six different aft-wise transverse step angles of 0°,9°,11°,13°,15°,and 17°at three speeds of 8,10,and 12 m/s.In the experimental tests,the hydrodynamic components of resistance,trim angle,and wetted surface of the vessel were measured.Results indicate that creating an angle in the transverse step substantially improves the hydrodynamic components and longitudinal stability of the vessel.At the optimal angle,the resistance and trim angle of the vessel were reduced by 7.8%and 12.8%,respectively,compared to the base vessel.Additionally,the existing analytical methods for calculating the wetted surface area are more accurate than similar methods.展开更多
An analysis is conducted on the hydrodynamic response law of a single module maritime airport,considering the atmospheric variables of the wind and wave field.The analysis is based on hydroelastic theory and focuses o...An analysis is conducted on the hydrodynamic response law of a single module maritime airport,considering the atmospheric variables of the wind and wave field.The analysis is based on hydroelastic theory and focuses on the typhoon-driven very large floating structures(VLFS)configuration of the maritime airport.The findings indicate that the proposed method enables efficient information exchange between the fluid and structure domains through the coupling interface.The displacement of the maritime airport affected by the typhoon’s wave field is mostly determined by the direction of the flow.The wave loads acting on the floating body also influence the wave profile of the irregular wave and the deformation of the floating body.The von Mises stress distribution is not significant in all parts of the floating body.展开更多
To meet the intelligent detection needs of underwater defects in large hydropower stations,the hydrodynamic performance of a bionic streamlined remotely operated vehicle containing a thruster protective net structure ...To meet the intelligent detection needs of underwater defects in large hydropower stations,the hydrodynamic performance of a bionic streamlined remotely operated vehicle containing a thruster protective net structure is numerically simulated via computational fluid dynamics and overlapping mesh technology.The results show that the entity model generates greater hydrodynamic force during steady motion,whereas the square net model experiences greater force and moment during unsteady motion.The lateral and vertical force coefficients of the entity model are 4.32 and 3.13 times greater than those of the square net model in the oblique towing test simulation.The square net model also offers better static and dynamic stability,with a 24.5%increase in dynamic stability,achieving the highest lift-to-drag ratio at attack angles of 6°∼8°.This research provides valuable insights for designing and controlling underwater defect detection vehicles for large hydropower stations.展开更多
The Hydrodynamic Ram(HRAM)effect occurs when a high kinetic energy projectile penetrates a fluid filled area,e.g.,a liquid filled tank.The projectile transfers its momentum and kinetic energy to the fluid,what causes ...The Hydrodynamic Ram(HRAM)effect occurs when a high kinetic energy projectile penetrates a fluid filled area,e.g.,a liquid filled tank.The projectile transfers its momentum and kinetic energy to the fluid,what causes a sudden,local pressure rise,further expanding as primary shock wave in the fluid and developing a cavity.It is possible that the entire tank ruptures due to the loads transferred through the fluid to its surrounding structure.In the past decades,additionally to experimental investigations,HRAM has been studied using various computational approaches particularly focusing on the description of the Fluid-Structure Interaction(FSI).This article reviews the published experimental,analytical and numerical results and delivers a chronological overview since the end of World War II.Furthermore,HRAM mitigation measures are highlighted,which have been developed with the experimental,analytical and numerical toolboxes matured over the past 80 years.展开更多
This study presents a comparative analysis of optimisation strategies for designing hull shapes of Autonomous Underwater Vehicles(AUVs),paying special attention to drag,lift-to-drag ratio,and delivered power.A fully i...This study presents a comparative analysis of optimisation strategies for designing hull shapes of Autonomous Underwater Vehicles(AUVs),paying special attention to drag,lift-to-drag ratio,and delivered power.A fully integrated optimisation framework is developed accordingly,combining a single-objective Genetic Algorithm(GA)for design parameter generation,Computer-Aided Geometric Design(CAGD)for the creation of hull geometries and associated fluid domains,and a Reynolds-Averaged Navier-Stokes(RANS)solver for evaluating hydrodynamic performance metrics.This unified approach eliminates manual intervention,enabling automated determination of optimal hull configurations.Three distinct optimisation problems are addressed using the proposed methodology.First,the drag minimisation of a reference afterbody geometry(A1)at zero angle of attack is performed under constraints of fixed length and internal volume for various flow velocities spanning the range from 0.5 to 15 m/s.Second,the lift-to-drag ratio of A1 is maximised at a 6°angle of attack,maintaining constant total length and internal volume.Third,delivered power is minimised for A1 at a 0°angle of attack.The comparative analysis of results from all three optimisation cases reveals hull shapes with practical design significance.Notably,the shape optimised for minimum delivered power outperforms the other two across a range of velocities.Specifically,it achieves reductions in required power by 7.6%,7.8%,10.2%,and 13.04%at velocities of 0.5,1.0,1.5,and 2.152 m/s,respectively.展开更多
基金funded by the National Key R&D Program of China(Grant No.2023YFA1608400)the National Natural Science Foundation of China(Grant No.12302281).
文摘Hydrodynamic instability growth at the deuterium-tritium(DT)fuel-ablator interface plays a critical role in determining the performance of inertial confinement fusion implosions.During the late stages of implosion,insufficient doping of the ablator material can result in highenergy X-ray preheat,which may trigger the development of a classical-like Rayleigh-Taylor instability(RTI)at the fuel-ablator interface.In implosion experiments at the Shenguang 100 kJ-level laser facility,the primary source of perturbation is the roughness of the inner DT ice interface.In this study,we propose an analytical model to describe the feed-out process of the initial roughness of the inner DT ice interface.The perturbation amplitude derived from this model serves as the initial seed for the late-time RTI during the acceleration phase.Our findings confirm the presence of classical-like RTI at the fuel-ablator interface.Numerical simulations conducted using a radiation hydrodynamic code validate the proposed analytical model and demonstrate the existence of a peak mode number in both the feed-out process and the classical-like RTI.It provides an alternative bridge between the current target fabrication limitations and the unexpected implosion performance.
基金supported by the Swedish Research Council(VR)under grant number 2020-05044by the research environment grant"Gravitational Radiation and Electromagnetic Astrophysical Transients"(GREAT)funded by the Swedish Research Council(VR)under Dnr 2016-06012+2 种基金by the Knut and Alice Wallenberg Foundation under grant Dnr.KAW 2019.0112by the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)under Germany's Excellence Strategy-EXC 2121"Quantum Universe"-390833306by the European Research Council(ERC)Advanced Grant INSPIRATION under the European Union's Horizon 2020 Research and Innovation Programme(Grant agreement No.101053985).
文摘We present and explore a new shock-capturing particle hydrodynamics approach.Our starting point is a commonly used discretization of smoothed particle hydrodynamics.We enhance this discretization with Roe’s approx-imate Riemann solver,we identify its dissipative terms,and in these terms,we use slope-limited linear reconstruction.All gradients needed for our method are calculated with linearly reproducing kernels that are constructed to enforce the two lowest-order consistency relations.We scrutinize our reproducing kernel implementation carefully on a“glass-like”particle distribution,and we find that constant and linear functions are recovered to machine precision.We probe our method in a series of challenging 3D benchmark problems ranging from shocks over instabilities to Schulz-Rinne-type vorticity-creating shocks.All of our simulations show excellent agreement with analytic/reference solutions.
基金Supported by the National Natural Science Foundation of China(Nos.52222904 and 52309117)China Postdoctoral Science Foundation(Nos.2022TQ0168 and 2023M731895).
文摘Ocean energy has progressively gained considerable interest due to its sufficient potential to meet the world’s energy demand,and the blade is the core component in electricity generation from the ocean current.However,the widened hydraulic excitation frequency may satisfy the blade resonance due to the time variation in the velocity and angle of attack of the ocean current,even resulting in blade fatigue and destructively interfering with grid stability.A key parameter that determines the resonance amplitude of the blade is the hydrodynamic damping ratio(HDR).However,HDR is difficult to obtain due to the complex fluid-structure interaction(FSI).Therefore,a literature review was conducted on the hydrodynamic damping characteristics of blade-like structures.The experimental and simulation methods used to identify and obtain the HDR quantitatively were described,placing emphasis on the experimental processes and simulation setups.Moreover,the accuracy and efficiency of different simulation methods were compared,and the modal work approach was recommended.The effects of key typical parameters,including flow velocity,angle of attack,gap,rotational speed,and cavitation,on the HDR were then summarized,and the suggestions on operating conditions were presented from the perspective of increasing the HDR.Subsequently,considering multiple flow parameters,several theoretical derivations and semi-empirical prediction formulas for HDR were introduced,and the accuracy and application were discussed.Based on the shortcomings of the existing research,the direction of future research was finally determined.The current work offers a clear understanding of the HDR of blade-like structures,which could improve the evaluation accuracy of flow-induced vibration in the design stage.
基金National Natural Science Foundation of China(12471367)。
文摘In this work,we present a parallel implementation of radiation hydrodynamics coupled with particle transport,utilizing software infrastructure JASMIN(J Adaptive Structured Meshes applications INfrastructure)which encapsulates high-performance technology for the numerical simulation of complex applications.Two serial codes,radiation hydrodynamics RH2D and particle transport Sn2D,have been integrated into RHSn2D on JASMIN infrastructure,which can efficiently use thousands of processors to simulate the complex multi-physics phenomena.Moreover,the non-conforming processors strategy has ensured RHSn2D against the serious load imbalance between radiation hydrodynamics and particle transport for large scale parallel simulations.Numerical results show that RHSn2D achieves a parallel efficiency of 17.1%using 90720 cells on 8192 processors compared with 256 processors in the same problem.
基金supported by Environmental Protection Project 2023-2024,with the Joint Vietnam-Russia Tropical Science and Technology Research Center(Southern Branch)as the lead Institution.
文摘Mangrove ecosystems along Vietnam’s coastline face significant degradation due to human activities,despite their crucial role in coastal protection against natural hazards.This study aims to assess the spatial and temporal changes in mangrove coverage along Vietnam’s southern coast by integrating remote sensing techniques with hydrodynamic model simulations.The research methodology combines the Collect Earth tool analysis of Spot-4 and Planet satellite imagery(2000–2020)with Mike 21-HD two-dimensional(2D)hydrodynamic modeling to evaluate mangrove coverage changes by simulating shoreline erosion.Results analysis reveals that a significant increase of 109.83 ha in mangrove area within Vinh Chau Town of Soc Trang Province during the period 2010–2020,predominantly in the eastern region.Hydrodynamic simulations demonstrate that the coastal zone is primarily influenced by the interaction of nearshore currents,East Sea tides,and seasonal monsoon wave patterns.The model results effectively capture the complex interactions between these hydrodynamic factors and mangrove distribution.These findings not only validate the effectiveness of combining remote sensing and hydrodynamic modeling for mangrove assessment but also provide crucial insights for sustainable coastal ecosystem management.The study’s integrated approach offers a robust framework for monitoring mangrove dynamics and developing evidence-based conservation strategies,highlighting the importance of maintaining these vital ecosystems for coastal protection.
基金supported by the National Natural Science Foundation of China(Nos.22136003 and 21972073)the Opening foundation of the Engineering Research Center of Ecoenvironment in Three Gorges Reservoir Region,Ministry of Education(No.KF2023-01)the Natural Science Foundation of Yichang City(No.A22-3-005)。
文摘The synergetic technology of hydrodynamic cavitation(HC)and peroxydisulfate(PDS)has been adopted for the treatment of organic pollutants,while the rationale behind the thermal-activation of PDS in this process remains lacking.This paper presented investigation on the degradation of tetracycline under two types of operating conditions,including“internal reaction conditions”(pH value and TC/PDS molar ratio)and“external physical conditions”(hole shape,solution temperature and inlet pressure).Special emphasis was paid on the analysis of thermal effects through a robust modeling approach.The results showed that a synergy index of 6.26 and a degradation rate of 56.71%could be obtained by the HC-PDS process,respectively,when the reaction conditions were optimized.Quenching experiment revealed that·OH and·SO_(4)^(-)were the predominant free radicals and their contribution to the degradation was 75.4%and 24.6%respectively,since a part of·SO_(4)^(-)was transformed into·OH in the solution.The thermal activation of PDS mainly occurred near the hole where the fitting temperature was around 340 K,while·OH was generated in the bubble collapse region downstream the hole,where the temperature was much higher and favorable for the cleavage of water molecular.The average temperature under different external physical conditions was in good consistence with the degradation rates.This research developed a useful method to effectively evaluate the activation extent of PDS by HC and could provide reliable guidance for further development of cavitational reactors to treat organic pollutants based on this hybrid approach.
基金supported by the National Natural Science Foundation of China(Grant Nos.12365007 and 12265017)Yunnan Fundamental Research Projects(Grant Nos.202101AS070018 and 202101AV070015)+1 种基金the Scientific Research Foundation of the Yunnan Provincial Department of Education(Grant No.2023J1208)Xingdian Talents Support Program,and Yunnan Province Ten Thousand Talents Plan Young&Elite Talents Project,and Yunnan Province Computational Physics and Applied Science and Technology Innovation Team.The numerical simulation and significance estimation were performed on the Key Laboratory of High-Density Computing,Zhaotong University。
文摘Particle transport is a fundamental aspect of various systems,from artificial to biological.A common assumption is that particle motion follows Markovian(memoryless)processes in the absence of interaction between particles.However,hydrodynamic memory and the interaction between particles are ubiquitous,leaving many fundamental questions unanswered regarding transport of interacting particles involving hydrodynamic drag in corrugated channels,as described by the fractional Langevin equation.This study examines the hydrodynamic transport of interacting non-Brownian particles moving within a corrugated channel.We propose a method that relies on factors such as temperature,the driving force to alternate between no transport and finite net transport.Of importance is to note that the absence of transport results from the clogging,while the transport consists of collective motion and independent motion.The transport systems investigated in this work suggest the potential for sensor functionality within the system.Our findings may prove valuable for exploring the transport with hydrodynamic memory in various fields,including biology,physics,and chemistry.
文摘Rip currents are a significant threat to swimmers worldwide,responsible for numerous drowning incidents each year.In Vietnam,Bai Dai Beach in Cam Ranh Bay,Khanh Hoa Province,has experienced an increase in drowning events due to rip currents in recent years.To address this issue,a comprehensive study was conducted based on developing a depth-averaged 2D hydrodynamic model to simulate rip currents in the Bai Dai-Cam Ranh coast.The HYDIST-2D numerical model was applied to simulate the rip current evolution in space and time for the study area.The results showed that the HYDIST-2D numerical model can accurately predict the location,magnitude,and microstructure of rip currents,including rip current speed,width,and length.The simulation results revealed that the rip current speed is greater during the low tide phase,with an average speed of 0.5 m s^(-1),while during high tide,the rip current speed is lower,around 0.1–0.8 m s^(-1).The width and length of the rip current also vary with the tide phase,with a wider and longer rip current observed during the low tide phase.The results also showed that the rip current speed and microstructure are influenced by the wave features,tide current,and bathymetry of the study area.The present study provides valuable insights into the dynamics of rip currents in the Bai Dai-Cam Ranh coast.The findings can be used to support the management of bathing activities and provide early warnings for potential risks associated with rip currents.
基金financially supported by the National Natural Science Foundation of China(Grant No.52088102)New Cornerstone Science Foundation through the XPLORER PRIZE.
文摘Floating breakwaters(FBs)are commonly employed for the protection of coastal installations.In this work,a convextype floating breakwater(FB)is proposed,and its hydrodynamic characteristics are studied through systematic laboratory experiments.Two different deck widths and two different mooring systems are set in the experiment.The transmission coefficients,reflection coefficients,motion responses and mooring forces of convex-type FBs are obtained in experiments.The influences of the deck width and mooring system on the hydrodynamic characteristics of the proposed FB are analyzed and compared.The experimental results show that the reflection coefficient and mooring force of the convex-type FB with a cross-mooring system are significantly larger than those of the convextype FB with a parallel-mooring system.A convex-type FB with a larger deck width has a higher reflection coefficient.The convex-type FBs with cross-and parallel-mooring systems have similar surge and heave motions,but the cross-mooring results in small roll motion.In addition,reliable prediction formulas for the transmission coefficient of convex-type FBs with different mooring systems have been developed,which are important for engineering design.
基金funded by the Science and Technology Project of Tianjin(No.24YDTPJC00680)the National Natural Science Foundation of China(No.52406191).
文摘The growth of computing power in data centers(DCs)leads to an increase in energy consumption and noise pollution of air cooling systems.Chip-level cooling with high-efficiency coolant is one of the promising methods to address the cooling challenge for high-power devices in DCs.Hybrid nanofluid(HNF)has the advantages of high thermal conductivity and good rheological properties.This study summarizes the numerical investigations of HNFs in mini/micro heat sinks,including the numerical methods,hydrothermal characteristics,and enhanced heat transfer technologies.The innovations of this paper include:(1)the characteristics,applicable conditions,and scenarios of each theoretical method and numerical method are clarified;(2)the molecular dynamics(MD)simulation can reveal the synergy effect,micro motion,and agglomeration morphology of different nanoparticles.Machine learning(ML)presents a feasiblemethod for parameter prediction,which provides the opportunity for the intelligent regulation of the thermal performance of HNFs;(3)the HNFs flowboiling and the synergy of passive and active technologies may further improve the overall efficiency of liquid cooling systems in DCs.This review provides valuable insights and references for exploring the multi-phase flow and heat transport mechanisms of HNFs,and promoting the practical application of HNFs in chip-level liquid cooling in DCs.
基金the National Natural Science Foundation of China (No. 51905211)China Postdoctoral Science Foundation (Grant No. 2020M672128)+1 种基金University of Jinan Research Startup and Discipline Construction Fund (Grant No.1009435)a Project of the “20 Regulations for New Universities” funding program of Jinan (No.202228116)。
文摘Pulsating flow is a common condition for under water manipulators in Bohai Bay.This study aimed to investigate the effects of pulsation frequency and amplitude on the hydrodynamic characteristics of an underwater manipulator with different postures using the user-defined function (UDF) method. The lift coefficient (C_(L)), drag coefficient (C_(D)), and vortex shedding of the underwater manipulator in single-and dualarm forms were obtained. Results indicated that the maximum increase in the lift and drag coefficients subjected to the pulsation parameters was 24.45%and 28%, respectively, when the fluid flowed past a single arm. Compared with the single arm, the lift and drag coefficients of the arms were higher than those of the single arm when arm 2 was located upstream. Additionally, the pulsation frequency had no obvious effect on the manipulator, but the C_(L) and C_(D) of arm 2 showed an obvious increasing trend with an increase in pulsation amplitude. Meanwhile, when arm 2 was located downstream, the C_(L) and C_(D) of arm 2 were reduced by 16.38%and 1.15%, respectively, with an increase in the pulse frequency,and the maximum increase in the lift and dragcoefficients was 33.33%and 16.78%,respectively,with increasing pulsation amplitude.Moreover, the downstream wake morphology changed significantly, and a combined vortex phenomenon appeared. Finally, a theoretical basis for examining the hydrodynamic characteristics of marine engineering equipment was established to aid future marine resource exploitation.
基金Supported by Shandong Provincial Natural Science Foundation,China(ZR2020ME259)Open Fund of Shandong Key Laboratory of Civil Engineering Disaster Prevention and Mitigation(CDPM2021KF21).
文摘Two asymmetric types of floating breakwaters integrated with a wave energy converter(WEC-FBs),a floating square box with a triangle(trapezoidal type)or a wave baffle(L type)attached to its rear side,have been proposed.In this research,the hydrodynamic performance,including capture width ratio(CWR),wave transmission coefficient,heave motion,and force coefficient,were studied and compared between the two types.A numerical simulation model based on the Navier-Stokes equation was employed.The effects of power take-off(PTO)damping coefficient,wave periods,and draft/displacement on the hydrodynamic performance of the two structure shapes were simulated and investigated.The results reveal that the L type performs better in shorter wave periods,and the trapezoidal type exhibits a higher CWR in intermediate wave periods.This study offers knowledge of the design and protection of the two WEC-FB types.
基金sponsored by the National Natural Science Foundation of China(Grant No.32373187)the Research Fund for International Scientists of the National Natural Science Foundation of China(Grant No.32350410404)the Natural Science Foundation of Shanghai(Grant No.23ZR1427000).
文摘This study experimentally investigates the hydrodynamic characteristics,geometric configurations,fluttering motions of the codend,and the instantaneous flow fields inside and around the codend,with and without a liner,under varying catch sizes and inflow velocities.A proper orthogonal decomposition method is employed to extract phase-averaged mean properties of unsteady turbulent flows from flow measurement data obtained using an electromagnetic current velocity meter inside and around the codend.The results reveal that as catch size increases,the drag force,codend motion,Reynolds number,and codend volume increase while the drag coefficient decreases.Owing to the codend shape and pronounced motion,a complex fluid–structure interaction occurs,demonstrating a strong correlation between drag force and codend volume.The oscillation amplitudes of the hydrodynamic forces and codend motions increase with increasing catch size,and their oscillations mainly involve low-frequency activity.A significant reduction in the flow field occurs inside and around the unlined codend without a catch.The flow field is 5.81%,14.39%,and 27.01%lower than the unlined codend with a catch,the codend with a liner but without a catch,and the codend with both a liner and a catch,respectively.Fourier analysis reveals that the codend motions and hydrodynamic forces are mainly characterized by low-frequency activity and are synchronized with the unsteady turbulent flow street.Furthermore,the proper orthogonal decomposition results reveal the development of unsteady turbulent flow inside and around the codend,driven by flow passage blockage caused by the presence of the liner,intense codend motions,and the catch.Understanding the hydrodynamic characteristics and flow instabilities inside and around the codend,particularly those associated with its fluttering motions,is crucial for optimizing trawl design and improving trawl selectivity.
基金supported by the National Natural Science Foundation of China(Nos.52271295,52088102).
文摘To propel the application of a bottom-hinged flap breakwater in real sea conditions,a two-dimensional computational fluid dynamics numerical model was conducted to investigate the pitching motion response and wave attenuation in random waves.First,the flow velocity distribution characteristic of the pitching flap at typical times was summarized.Then,the effects of random wave and flap parameters on the flap’s significant pitching angle amplitude θ_(s) and hydrodynamic coefficients were investigated.The results reveal that θ_(s) and wave reflection coefficient K_(r) values increase with increasing significant wave height Hs,random wave steepnessλs,and flap relative height.As Hs andλs increase,the wave transmission coefficient K_(t) increases while the wave dissipation coefficient K_(d) decreases.Additionally,K_(t) decreases with increasing flap relative height.With increasing equivalent damping coefficient ratio,θ_(s) and K_(t) decrease,while K_(r) and K_(d) increase.The relationships betweenλs and flap relative height on the one hand andθ_(s),K_(r),K_(t),and K_(d) in random waves on the other hand are compared to those in regular waves.Based on the equal incident wave energy and the equal incident wave energy flux,the pitching flap performs better in the wave attenuation capability under random waves than in regular waves.Finally,the dimensionless parameters with respect to random wave and flap were used to derive the K_(r) and K_(t) for-mulae,which were validated with the related data.
基金The National Natural Science Foundation of China(No.52222804,U21A20154).
文摘Past investigations of the hydrodynamic forces on vertical columns have generally been based on rigid structure assumptions.The effects of structural flexibility and geometry characteristics on the hydrodynamic force distribution are not well understood.In this study,fluid-structure interaction models are developed for numerical analyses.This modeling technique is verified with an experimental test in the literature using both circular and rectangular cross-sections.A series of material elasticities that present structural properties ranging from rigid to flexible is then used to conduct analyses.This finding indicates that an increase in structural flexibility can decrease the impact force to some extent,but this effect is limited.A concrete bridge pier with fluid flow impact can be considered rigid when it is fixed at the bottom.After that,the effects of the initial downstream water height and the width of water tank on the hydrodynamic force are thoroughly investigated.The results demonstrate that the increase in the downstream water height with a constant upstream water height corresponds to a decreased force.Moreover,the vertical column results in a blockage effect on the fluid flow.The greater the blockage effect,the higher the hydrodynamic force.The blockage effect from the vertical column can be neglected when the tank width is greater than eight times the structural cross-section diameter.
文摘demand for faster vessels continues to grow,various high speed vessels have been designed and constructed for military,recreational,and passenger use.Planing vessels,specifically engineered for high-speed travel,require optimization to improve their hydrodynamic performance and stability during design.Reducing resistance and improving longitudinal stability are key challenges in the design of high-speed vessels.Various methods are employed to overcome these challenges,with the use of a transverse step being one of the most common approaches.This study explores the effect of changing the angle of the aft-wise step and incorporates these changes into existing analytical formulas,resulting in new formulas specifically for high-speed vessels equipped with aft-wise steps.This research investigates how the angle of the transverse step affects the hydrodynamic performance and longitudinal stability of high-speed vessels.Based on the results,analytical formulas have been developed to calculate the wetted surface parameters of vessels equipped with an aft-wise transverse step.The study used experimental methods to analyze the vessel's behavior with six different aft-wise transverse step angles of 0°,9°,11°,13°,15°,and 17°at three speeds of 8,10,and 12 m/s.In the experimental tests,the hydrodynamic components of resistance,trim angle,and wetted surface of the vessel were measured.Results indicate that creating an angle in the transverse step substantially improves the hydrodynamic components and longitudinal stability of the vessel.At the optimal angle,the resistance and trim angle of the vessel were reduced by 7.8%and 12.8%,respectively,compared to the base vessel.Additionally,the existing analytical methods for calculating the wetted surface area are more accurate than similar methods.
基金supported in part by the National Natural Science Foundation of China(No.51761165022)the Natural Science Foundation of Jiangsu Province(No.BK20210309)the Jiangsu Graduate Research and Practice Innovation Program(No.KYCX21_0234)。
文摘An analysis is conducted on the hydrodynamic response law of a single module maritime airport,considering the atmospheric variables of the wind and wave field.The analysis is based on hydroelastic theory and focuses on the typhoon-driven very large floating structures(VLFS)configuration of the maritime airport.The findings indicate that the proposed method enables efficient information exchange between the fluid and structure domains through the coupling interface.The displacement of the maritime airport affected by the typhoon’s wave field is mostly determined by the direction of the flow.The wave loads acting on the floating body also influence the wave profile of the irregular wave and the deformation of the floating body.The von Mises stress distribution is not significant in all parts of the floating body.
基金supported by the National Key R&D Program of China(Grant No.2022YFB4703401).
文摘To meet the intelligent detection needs of underwater defects in large hydropower stations,the hydrodynamic performance of a bionic streamlined remotely operated vehicle containing a thruster protective net structure is numerically simulated via computational fluid dynamics and overlapping mesh technology.The results show that the entity model generates greater hydrodynamic force during steady motion,whereas the square net model experiences greater force and moment during unsteady motion.The lateral and vertical force coefficients of the entity model are 4.32 and 3.13 times greater than those of the square net model in the oblique towing test simulation.The square net model also offers better static and dynamic stability,with a 24.5%increase in dynamic stability,achieving the highest lift-to-drag ratio at attack angles of 6°∼8°.This research provides valuable insights for designing and controlling underwater defect detection vehicles for large hydropower stations.
文摘The Hydrodynamic Ram(HRAM)effect occurs when a high kinetic energy projectile penetrates a fluid filled area,e.g.,a liquid filled tank.The projectile transfers its momentum and kinetic energy to the fluid,what causes a sudden,local pressure rise,further expanding as primary shock wave in the fluid and developing a cavity.It is possible that the entire tank ruptures due to the loads transferred through the fluid to its surrounding structure.In the past decades,additionally to experimental investigations,HRAM has been studied using various computational approaches particularly focusing on the description of the Fluid-Structure Interaction(FSI).This article reviews the published experimental,analytical and numerical results and delivers a chronological overview since the end of World War II.Furthermore,HRAM mitigation measures are highlighted,which have been developed with the experimental,analytical and numerical toolboxes matured over the past 80 years.
文摘This study presents a comparative analysis of optimisation strategies for designing hull shapes of Autonomous Underwater Vehicles(AUVs),paying special attention to drag,lift-to-drag ratio,and delivered power.A fully integrated optimisation framework is developed accordingly,combining a single-objective Genetic Algorithm(GA)for design parameter generation,Computer-Aided Geometric Design(CAGD)for the creation of hull geometries and associated fluid domains,and a Reynolds-Averaged Navier-Stokes(RANS)solver for evaluating hydrodynamic performance metrics.This unified approach eliminates manual intervention,enabling automated determination of optimal hull configurations.Three distinct optimisation problems are addressed using the proposed methodology.First,the drag minimisation of a reference afterbody geometry(A1)at zero angle of attack is performed under constraints of fixed length and internal volume for various flow velocities spanning the range from 0.5 to 15 m/s.Second,the lift-to-drag ratio of A1 is maximised at a 6°angle of attack,maintaining constant total length and internal volume.Third,delivered power is minimised for A1 at a 0°angle of attack.The comparative analysis of results from all three optimisation cases reveals hull shapes with practical design significance.Notably,the shape optimised for minimum delivered power outperforms the other two across a range of velocities.Specifically,it achieves reductions in required power by 7.6%,7.8%,10.2%,and 13.04%at velocities of 0.5,1.0,1.5,and 2.152 m/s,respectively.
