Aptamers are a type of single-chain oligonucleotide that can combine with a specific target.Due to their simple preparation,easy modification,stable structure and reusability,aptamers have been widely applied as bioch...Aptamers are a type of single-chain oligonucleotide that can combine with a specific target.Due to their simple preparation,easy modification,stable structure and reusability,aptamers have been widely applied as biochemical sensors for medicine,food safety and environmental monitoring.However,there is little research on aptamer-target binding mechanisms,which limits their application and development.Computational simulation has gained much attention for revealing aptamer-target binding mechanisms at the atomic level.This work summarizes the main simulation methods used in the mechanistic analysis of aptamer-target complexes,the characteristics of binding between aptamers and different targets(metal ions,small organic molecules,biomacromolecules,cells,bacteria and viruses),the types of aptamer-target interactions and the factors influencing their strength.It provides a reference for further use of simulations in understanding aptamer-target binding mechanisms.展开更多
Two-dimensional(2D) nanomaterials have always been regarded as having great development potential in the field of oil-based lubrication due to their designable structures,functional groups,and abundant active sites.Ho...Two-dimensional(2D) nanomaterials have always been regarded as having great development potential in the field of oil-based lubrication due to their designable structures,functional groups,and abundant active sites.However,understanding the structure-performance relationship between the chemical structure of 2D nanomaterials and their lubrication performance from a comprehensive perspective is crucial for guiding their future development.This review provides a timely and comprehensive overview of the applications of 2D nanomaterials in oil-based lubrication.First,the bottlenecks and mechanisms of action of 2D nanomaterials are outlined,including adsorption protective films,charge adsorption effects,tribochemical reaction films,interlayer slip,and synergistic effects.On this basis,the review summarizes recent structural regulation strategies for 2D nanomaterials,including doping engineering,surface modification,structural optimization,and interfacial mixing engineering.Then,the focus was on analyzing the structure-performance relationship between the chemical structure of 2D nanomaterials and their lubrication performance.The effects of thickness,number of layers,sheet diameter,interlayer spacing,Moiré patterns,wettability,functional groups,concentration,as well as interfacial compatibility and dispersion behavior of 2D nanomaterials were systematically investigated in oil-based lubrication,with the intrinsic correlations resolved through computational simulations.Finally,the review offers a preliminary summary of the significant challenges and future directions for 2D nanomaterials in oil-based lubrication.This review aims to provide valuable insights and development strategies for the rational design of high-performance oil-based lubrication materials.展开更多
Over the last decade, computational methods have been intensively applied to a variety of scientific researches and engineering designs. Although the computational fluid dynamics （CFD） method has played a dominant r...Over the last decade, computational methods have been intensively applied to a variety of scientific researches and engineering designs. Although the computational fluid dynamics （CFD） method has played a dominant role in studying and simulating transport phenomena involving fluid flow and heat and mass transfers, in recent years, other numerical methods for the simulations at meso- and micro-scales have also been actively applied to solve the physics of complex flow and fluid-interface interactions. This paper presents a review of recent advances in multi-scale computational simulation of biomimetics related fluid flow problems. The state-of-the-art numerical techniques, such as lattice Boltzmann method （LBM）, molecular dynamics （MD）, and conventional CFD, applied to different problems such as fish flow, electro-osmosis effect of earthworm motion, and self-cleaning hydrophobic surface, and the numerical approaches are introduced. The new challenging of modelling biomimetics problems in developing the physical conditions of self-clean hydrophobic surfaces is discussed.展开更多
In order to simulate the instability phenomenon of a nonaqueous phase liquid(NAPL) dissolution front in a computational model, the intrinsic characteristic length is commonly used to determine the length scale at whic...In order to simulate the instability phenomenon of a nonaqueous phase liquid(NAPL) dissolution front in a computational model, the intrinsic characteristic length is commonly used to determine the length scale at which the instability of the NAPL dissolution front can be initiated. This will require a huge number of finite elements if a whole NAPL dissolution system is simulated in the computational model. Even though modern supercomputers might be used to tackle this kind of NAPL dissolution problem, it can become prohibitive for commonly-used personal computers to do so. The main purpose of this work is to investigate whether or not the whole NAPL dissolution system of an annular domain can be replaced by a trapezoidal domain, so as to greatly reduce the requirements for computer efforts. The related simulation results have demonstrated that when the NAPL dissolution system under consideration is in a subcritical state, if the dissolution pattern around the entrance of an annulus domain is of interest, then a trapezoidal domain cannot be used to replace an annular domain in the computational simulation of the NAPL dissolution system.However, if the dissolution pattern away from the vicinity of the entrance of an annulus domain is of interest, then a trapezoidal domain can be used to replace an annular domain in the computational simulation of the NAPL dissolution system. When the NAPL dissolution system under consideration is in a supercritical state, a trapezoidal domain cannot be used to replace an annular domain in the computational simulation of the NAPL dissolution system.展开更多
Computational fluid dynamics（CFD） simulations are adopted to investigate rectangular microchannel flows with various periodic micro-structured wall by introducing velocity slip boundary condition at low Reynolds num...Computational fluid dynamics（CFD） simulations are adopted to investigate rectangular microchannel flows with various periodic micro-structured wall by introducing velocity slip boundary condition at low Reynolds number. The purpose of the current study is to numerically find out the effects of periodic micro-structured wall on the flow resistance in rectangular microchannel with the different spacings between microridges ranging from 15 to 60 pm. The simulative results indicate that pressure drop with different spacing between microridges increases linearly with flow velocity and decreases monotonically with slip velocity; Pressure drop reduction also increases with the spacing between microridges at the same condition of slip velocity and flow velocity. The results of numerical simulation are compared with theoretical predictions and experimental results in the literatures. It is found that there is qualitative agreement between them.展开更多
According to the recently developed single-trough floating machine with the world's largest volume(inflatable mechanical agitation flotation machine with volume of 320 m3) in China, the gas-fluid two-phase flow in...According to the recently developed single-trough floating machine with the world's largest volume(inflatable mechanical agitation flotation machine with volume of 320 m3) in China, the gas-fluid two-phase flow in flotation cell was simulated using computational fluid dynamics method. It is shown that hexahedral mesh scheme is more suitable for the complex structure of the flotation cell than tetrahedral mesh scheme, and a mesh quality ranging from 0.7 to 1.0 is obtained. Comparative studies of the standard k-ε, k-ω and realizable k-ε turbulence models were carried out. It is indicated that the standard k-ε turbulence model could give a result relatively close to the practice and the liquid phase flow field is well characterized. In addition, two obvious recirculation zones are formed in the mixing zones, and the pressure on the rotor and stator is well characterized. Furthermore, the simulation results using improved standard k-ε turbulence model show that surface tension coefficient of 0.072, drag model of Grace and coefficient of 4, and lift coefficient of 0.001 can be achieved. The research results suggest that gas-fluid two-phase flow in large flotation cell can be well simulated using computational fluid dynamics method.展开更多
The finite element method was used to solve fluid dynamic interaction problems between the crust and mantle of the Earth. To consider different mechanical behaviours, the lithosphere consisting of the crust and upper ...The finite element method was used to solve fluid dynamic interaction problems between the crust and mantle of the Earth. To consider different mechanical behaviours, the lithosphere consisting of the crust and upper mantle was simulated as fluid-saturated porous rocks, while the upper aesthenospheric part of the mantle was simulated as viscous fluids. Since the whole lithosphere was computationally simulated, the dynamic interaction between the crust and the upper mantle was appropriately considered. In particular, the mixing of mantle fluids and crustal fluids was simulated in the corresponding computational model. The related computational simulation results from an example problem demonstrate that the mantle fluids can flow into the crust and mix with the crustal fluids due to the resulting convective flows in the crust-mantle system. Likewise, the crustal fluids can also flow into the upper mantle and mix with the mantle fluids. This kind of fluids mixing and exchange is very important to the better understanding of the governing processes that control the ore body formation and mineralization in the upper crust of the Earth.展开更多
We investigated the effect of supply air rate and temperature on formaldehyde emission characteristics in an environment chamber.A three-dimensional computational fluid dynamics(CFD) chamber model for simulating forma...We investigated the effect of supply air rate and temperature on formaldehyde emission characteristics in an environment chamber.A three-dimensional computational fluid dynamics(CFD) chamber model for simulating formaldehyde emission in twelve different cases was developed for obtaining formaldehyde concentration by the area-weighted average method.Laboratory experiments were conducted in an environment chamber to validate the simulation results of twelve different cases and the formaldehyde concentration was measured by continuous sampling.The results show that there was good agreement between the model prediction and the experimental values within 4.3 difference for each case.The CFD simulation results varied in the range from 0.21 mg/m3 to 0.94 mg/m3,and the measuring results in the range from 0.17 mg/m3 to 0.87 mg/m3.The variation trend of formaldehyde concentration with supply air rate and temperature variation for CFD simulation and experiment measuring was consistent.With the existence of steady formaldehyde emission sources,formaldehyde concentration generally increased with the increase of temperature,and it decreased with the increase of air supply rate.We also provided some reasonable suggestions to reduce formaldehyde concentration and to improve indoor air quality for newly decorated rooms.展开更多
The dysfunction of coronary microcirculation is an important cause of coronary artery disease(CAD).The index of microcirculatory resistance(IMR)is a quantitative evaluation of coronary microcirculatory function,which ...The dysfunction of coronary microcirculation is an important cause of coronary artery disease(CAD).The index of microcirculatory resistance(IMR)is a quantitative evaluation of coronary microcirculatory function,which provides a significant reference for the prediction,diagnosis,treatment,and prognosis of CAD.IMR also plays a key role in investigating the interaction between epicardial and microcirculatory dysfunctions,and is closely associated with coronary hemodynamic parameters such as flow rate,distal coronary pressure,and aortic pressure,which have been widely applied in computational studies of CAD.However,there is currently a lack of consensus across studies on the normal and pathological ranges of IMR.The relationships between IMR and coronary hemodynamic parameters have not been accurately quantified,which limits the application of IMR in computational CAD studies.In this paper,we discuss the research gaps between IMR and its potential applications in the computational simulation of CAD.Computational simulation based on the combination of IMR and other hemodynamic parameters is a promising technology to improve the diagnosis and guide clinical trials of CAD.展开更多
The cytochrome bc1complex(the bc1complex or complex Ⅲ) is an attractive target for the discovery of numerous pharmaceuticals and pesticides. In order to identify new lead structures for this target, a new series of m...The cytochrome bc1complex(the bc1complex or complex Ⅲ) is an attractive target for the discovery of numerous pharmaceuticals and pesticides. In order to identify new lead structures for this target, a new series of molecules, N-(4-aryloxyphenyl)phthalimides, were designed and synthesized in a straightforward manner. Our design strategy was to introduce a 4-aryloxyphenyl group, a fragment which exhibited promising bc1complex-inhibiting properties, into the aryl group of the valuable N-arylphthalimide backbone. Afterward, the biochemical evaluation of the newly synthesized compounds was carried out,and the results implied that several compounds demonstrated good activities against succinatecytochrome reductase(SCR, a mixture of mitochondrial complex Ⅱ and the bc1complex). Further studies confirmed that 3e’, a representative compound in this paper, was identified as an inhibitor of the bc1complex. Furthermore, computational simulations were also performed to better understand binding of 3e’ to the enzyme complex, which indicated that 3e’ should bind to the Qosite of the bc1complex.Consequently, we harbor the idea that this paper can provide a solid platform for synthesis and discovery of other bc1complex inhibitors.展开更多
The suspension characteristics of ultrafine powder slurry in the stirred vessel were simulated by using computational fluid dynamics.The results show that the Rushton disk turbine impeller is more conducive to maintai...The suspension characteristics of ultrafine powder slurry in the stirred vessel were simulated by using computational fluid dynamics.The results show that the Rushton disk turbine impeller is more conducive to maintaining suspended homogeneity and circulation of slurry compared with the pitch blade turbine pumping up impeller and the pitch blade turbine pumping down impeller.And the increase in stirring speed enhances turbulent fluctuation and anisotropic velocity of the fluid at the cost of more power consumption,which improves dispersibility and suspensibility of the particles.Meanwhile,the change of impeller clearance has a weak influence on the flow pattern,and the impeller clearance of 0.32T(T is the diameter of the bottom of the reactor)can achieve better dispersivity and suspensibility of the particles with lower power consumption and larger axial velocity.The experiments of surface coating modification of ultrafine titanium dioxide(TiO2)were carried out under the same conditions for those of the simulation system.The surface film morphology and photocatalytic properties of the modified TiO2 were analyzed,and the obtained data are well consistent with the simulation results.展开更多
In this work, we first investigated the hemodynamic parameters in the case of a normal aortic arch anatomy and in the case of aortic coarctation anatomy, both generated by using CFX-ICEM-ANSYS simulations. Then, we co...In this work, we first investigated the hemodynamic parameters in the case of a normal aortic arch anatomy and in the case of aortic coarctation anatomy, both generated by using CFX-ICEM-ANSYS simulations. Then, we compared these results with those obtained for a proposed model without and with aortic coarctation, while introducing a real tridimensional magnetic resonance imaging geometry in the simulation process. The conclusion is that our proposed model reproduces, with a high agreement, the real case obtained from imaging data.展开更多
The self-assembled structures of H_(3) BDA molecule with multiple meta-dicarboxylic groups and their stim-ulus responses to the vip molecules(COR and T4PT)are thoroughly investigated by scanning tunneling microscopy...The self-assembled structures of H_(3) BDA molecule with multiple meta-dicarboxylic groups and their stim-ulus responses to the vip molecules(COR and T4PT)are thoroughly investigated by scanning tunneling microscopy(STM).STM observations display that two kinds of nanostructures are fabricated by H3 BDA molecules through intermolecular hydrogen bonds,in which a linear structure is formed at a higher con-centration and a flower-like structure is obtained at a lower concentration.After the addition of COR and T4PT,H_(3) BDA appears different responsiveness resulting in different co-assembled structures,respectively.The linear structure is regulated into a flower-like structure by COR and COR molecules are trapped in the cavities.When the pyridine derivative(T4PT)is introduced,a new bicomponent porous structure emerges via the hydrogen bond formed between the carboxyl group and the pyridine.Furthermore,the deposition of additional COR to the H_(3) BDA/T4PT system results in the breakdown of the porous structure and the generation of H_(3) BDA/COR host-vip system.Combined with density functional theory(DFT)calculations and molecular dynamics(MD)simulations,the transformation phenomenon of bi-component nanostruc-ture induced by vip molecules is formulated.The results are expected to understand the modification effect of vip molecules on the host network,which is of great significance for the design and construc-tion of multi-component nanostructures and crystal engineering.展开更多
Fixed-bed reactors are generally considered the optimal choice for numerous multi-phase catalytic reactions due to their excellent performance and stability.However,conventional fixed beds often encounter challenges r...Fixed-bed reactors are generally considered the optimal choice for numerous multi-phase catalytic reactions due to their excellent performance and stability.However,conventional fixed beds often encounter challenges related to inadequate mass transfer and a high pressure drop caused by the non-uniform void fraction distribution.To enhance the overall performance of fixed beds,the impact of different packing configurations on performance was investigated.Experimental and simulation methods were used to investigate the fluid flow and mass transfer performances of various packed beds under different flow rates.It was found that structured beds exhibited a significantly lower pressure drop per unit length than conventional packed beds.Furthermore,the packing configurations had a critical role in improving the overall performance of fixed beds.Specifically,structured packed beds,particularly the H-2 packing configuration,effectively reduced the pressure drop per unit length and improved the mass transfer efficiency.The H-2 packing configuration consisted of two parallel strips of particles in each layer,with strips arranged perpendicularly between adjacent layers,and the spacing between the strips varied from layer to layer.展开更多
The design of three-dimensional printing based conformal cooling channels(CCCs)in injection molding holds great significance.Compared to CCCs,conformal cooling(CC)cavity solutions show promise in delivering enhanced c...The design of three-dimensional printing based conformal cooling channels(CCCs)in injection molding holds great significance.Compared to CCCs,conformal cooling(CC)cavity solutions show promise in delivering enhanced cooling performance for plastic products,although they have been underexplored.In this research,CC cavity is designed within the mold geometry,reinforced by body-centered cubic(BCC)lattice structures to enhance mechanical strength.Three distinct BCC lattice variations have been integrated into the CC cavity:the BCC structure,BCC with cubes,and BCC with pillars.The thermal performances of the BCC lattice-added CC cavity are assessed numerically after experimental validation.To provide feasible solutions from viewpoints of thermal performances,various BCC lattice structure thicknesses are analyzed in the range of 0.8–1.2mm.Thermal simulation outcomes reveal that thicker lattice structures enhance mechanical strength but simultaneously lead to an increase in cooling time.Upon examining all the proposed CC cavity solutions supported by BCC,the cooling times range from 2.2 to 4 s,resulting in a reduction of 38.6%to 66.1%when compared to conventional straightdrilled channels.In contrast to CCCs,CC cavities have the potential to decrease the maximum temperature nonuniformity from 8.5 to 6 K.Nevertheless,the presence of lattice structures in CC cavity solutions results in an elevated pressure drop,reaching 2.8MPa,whereas the results for CCCs remain below2.1MPa.展开更多
The structure of the concave-convex plates has proven to be crucial in optimizing the internal flow characteristics of the electrolyzer for hydrogen production.This paper investigates the impact of the gradual expansi...The structure of the concave-convex plates has proven to be crucial in optimizing the internal flow characteristics of the electrolyzer for hydrogen production.This paper investigates the impact of the gradual expansion angle of the inlet channel on the internal flow field of alkaline electrolyzers.The flow distribution characteristics of concave-convex plates with different inlet angle structures in the electrolytic cell is discussed.Besides,the system with internal heat source is studied.The results indicate that a moderate gradual expansion angle is beneficial for enhancing fluid uniformity.However,an excessively large gradual expansion angle may lead to adverse reflux phenomena,reducing the overall performance of the electrolytic cell.展开更多
The relationship between the site selection of a hilly terrain and the natural ventilation of the Dangdamen building complex,which is a traditional folk house,is revealed by a computational fluid dynamics（CFD）simula...The relationship between the site selection of a hilly terrain and the natural ventilation of the Dangdamen building complex,which is a traditional folk house,is revealed by a computational fluid dynamics（CFD）simulation.The wind press and speed distributions around the building in four cases with different weather conditions and topographies are simulated.The simulation results show that a hill can reduce the absolute values of the wind pressure at the windward and leeward sides of the building.The encouraging effect of the patio on the natural ventilation in a terrain with a hill is greater than that without a hill.The same situation occurs when comparing the patio effects between summer and winter.The wind speed around the building can be reduced by the hill as it is an obstacle and the degrees of the influence of the hill in summer and in winter are quite different because of different wind directions.The analysis results show that this kind of site selection,with the hill to the north,is a suitable way to settle the conflict of the natural ventilation requirements in summer and in winter under subtropical climate conditions,especially in houses with patios.展开更多
The flow distribution in quench tank for heat treatment of A357 alloy large complicated components was simulated using FLUENT computational fluid dynamics（CFD） software.The flow velocity and the uniformity of flow f...The flow distribution in quench tank for heat treatment of A357 alloy large complicated components was simulated using FLUENT computational fluid dynamics（CFD） software.The flow velocity and the uniformity of flow field in two types of quench tanks（with or without agitation system） were calculated.The results show that the flow field in the quench tank without agitation system has not evident regularity.While as for the quench tank with agitation system,the flow fields in different parameters have certain regularity.The agitation tanks have a distinct advantage over the system without agitation.Proper process parameters were also obtained.Finally,the tank model established in this work was testified by an example from publication.This model with high accuracy is able to optimize the tank structures and can be helpful for industrial production and theoretical investigation in the fields of heat treatment of large complicated components.展开更多
An open-source computational fluid dynamics（CFD）code named OpenFOAM is used to validate the flow field characteristics（flow patterns and pressure drop）around a single cylinder.Results show that OpenFOAM is suitabl...An open-source computational fluid dynamics（CFD）code named OpenFOAM is used to validate the flow field characteristics（flow patterns and pressure drop）around a single cylinder.Results show that OpenFOAM is suitable for simulating the low Reynolds number flow and Shaw＇s analytical expression is one of the solutions to Stokes＇ paradox.Experiments are performed on fibrous media and OpenFOAM simulation is carried out using the Tronville-Rivers two-dimensional random fiber model in terms of the characteristics of pressure drop.It is shown that the Kuwabara model predicts the pressure drop of fibrous filter media more accurately than the Happel model,and the experimental pressure drop is between simulated pressure drops with both non-slip and full-slip boundaries on fiber surfaces.展开更多
Diamond/metal composites are widely used in aerospace and electronic packaging fields due to their outstanding high thermal conductivity and low expansion.However,the difference in chemical properties leads to interfa...Diamond/metal composites are widely used in aerospace and electronic packaging fields due to their outstanding high thermal conductivity and low expansion.However,the difference in chemical properties leads to interface incompatibility between diamond and metal,which has a considerable impact on the performance of the composites.To improve the interface compatibility between diamond and metal,it is necessary to modify the interface of composites.This paper reviews the experimental research on interface modification and the application of computational simulation in diamond/metal composites.Combining computational simulation with experimental methods is a promising way to promote diamond/metal composite interface modification research.展开更多
文摘Aptamers are a type of single-chain oligonucleotide that can combine with a specific target.Due to their simple preparation,easy modification,stable structure and reusability,aptamers have been widely applied as biochemical sensors for medicine,food safety and environmental monitoring.However,there is little research on aptamer-target binding mechanisms,which limits their application and development.Computational simulation has gained much attention for revealing aptamer-target binding mechanisms at the atomic level.This work summarizes the main simulation methods used in the mechanistic analysis of aptamer-target complexes,the characteristics of binding between aptamers and different targets(metal ions,small organic molecules,biomacromolecules,cells,bacteria and viruses),the types of aptamer-target interactions and the factors influencing their strength.It provides a reference for further use of simulations in understanding aptamer-target binding mechanisms.
基金supported by the National Natural Science Foundation of China(No.51874036)the Natural Science Foundation of Ningxia(No.2024AAC02034)。
文摘Two-dimensional(2D) nanomaterials have always been regarded as having great development potential in the field of oil-based lubrication due to their designable structures,functional groups,and abundant active sites.However,understanding the structure-performance relationship between the chemical structure of 2D nanomaterials and their lubrication performance from a comprehensive perspective is crucial for guiding their future development.This review provides a timely and comprehensive overview of the applications of 2D nanomaterials in oil-based lubrication.First,the bottlenecks and mechanisms of action of 2D nanomaterials are outlined,including adsorption protective films,charge adsorption effects,tribochemical reaction films,interlayer slip,and synergistic effects.On this basis,the review summarizes recent structural regulation strategies for 2D nanomaterials,including doping engineering,surface modification,structural optimization,and interfacial mixing engineering.Then,the focus was on analyzing the structure-performance relationship between the chemical structure of 2D nanomaterials and their lubrication performance.The effects of thickness,number of layers,sheet diameter,interlayer spacing,Moiré patterns,wettability,functional groups,concentration,as well as interfacial compatibility and dispersion behavior of 2D nanomaterials were systematically investigated in oil-based lubrication,with the intrinsic correlations resolved through computational simulations.Finally,the review offers a preliminary summary of the significant challenges and future directions for 2D nanomaterials in oil-based lubrication.This review aims to provide valuable insights and development strategies for the rational design of high-performance oil-based lubrication materials.
文摘Over the last decade, computational methods have been intensively applied to a variety of scientific researches and engineering designs. Although the computational fluid dynamics （CFD） method has played a dominant role in studying and simulating transport phenomena involving fluid flow and heat and mass transfers, in recent years, other numerical methods for the simulations at meso- and micro-scales have also been actively applied to solve the physics of complex flow and fluid-interface interactions. This paper presents a review of recent advances in multi-scale computational simulation of biomimetics related fluid flow problems. The state-of-the-art numerical techniques, such as lattice Boltzmann method （LBM）, molecular dynamics （MD）, and conventional CFD, applied to different problems such as fish flow, electro-osmosis effect of earthworm motion, and self-cleaning hydrophobic surface, and the numerical approaches are introduced. The new challenging of modelling biomimetics problems in developing the physical conditions of self-clean hydrophobic surfaces is discussed.
基金Project(11272359)supported by the National Natural Science Foundation of China
文摘In order to simulate the instability phenomenon of a nonaqueous phase liquid(NAPL) dissolution front in a computational model, the intrinsic characteristic length is commonly used to determine the length scale at which the instability of the NAPL dissolution front can be initiated. This will require a huge number of finite elements if a whole NAPL dissolution system is simulated in the computational model. Even though modern supercomputers might be used to tackle this kind of NAPL dissolution problem, it can become prohibitive for commonly-used personal computers to do so. The main purpose of this work is to investigate whether or not the whole NAPL dissolution system of an annular domain can be replaced by a trapezoidal domain, so as to greatly reduce the requirements for computer efforts. The related simulation results have demonstrated that when the NAPL dissolution system under consideration is in a subcritical state, if the dissolution pattern around the entrance of an annulus domain is of interest, then a trapezoidal domain cannot be used to replace an annular domain in the computational simulation of the NAPL dissolution system.However, if the dissolution pattern away from the vicinity of the entrance of an annulus domain is of interest, then a trapezoidal domain can be used to replace an annular domain in the computational simulation of the NAPL dissolution system. When the NAPL dissolution system under consideration is in a supercritical state, a trapezoidal domain cannot be used to replace an annular domain in the computational simulation of the NAPL dissolution system.
基金National Natural Science Foundation of China (No.50435030)
文摘Computational fluid dynamics（CFD） simulations are adopted to investigate rectangular microchannel flows with various periodic micro-structured wall by introducing velocity slip boundary condition at low Reynolds number. The purpose of the current study is to numerically find out the effects of periodic micro-structured wall on the flow resistance in rectangular microchannel with the different spacings between microridges ranging from 15 to 60 pm. The simulative results indicate that pressure drop with different spacing between microridges increases linearly with flow velocity and decreases monotonically with slip velocity; Pressure drop reduction also increases with the spacing between microridges at the same condition of slip velocity and flow velocity. The results of numerical simulation are compared with theoretical predictions and experimental results in the literatures. It is found that there is qualitative agreement between them.
基金Project(51074027)supported by the National Natural Science Foundation of China
文摘According to the recently developed single-trough floating machine with the world's largest volume(inflatable mechanical agitation flotation machine with volume of 320 m3) in China, the gas-fluid two-phase flow in flotation cell was simulated using computational fluid dynamics method. It is shown that hexahedral mesh scheme is more suitable for the complex structure of the flotation cell than tetrahedral mesh scheme, and a mesh quality ranging from 0.7 to 1.0 is obtained. Comparative studies of the standard k-ε, k-ω and realizable k-ε turbulence models were carried out. It is indicated that the standard k-ε turbulence model could give a result relatively close to the practice and the liquid phase flow field is well characterized. In addition, two obvious recirculation zones are formed in the mixing zones, and the pressure on the rotor and stator is well characterized. Furthermore, the simulation results using improved standard k-ε turbulence model show that surface tension coefficient of 0.072, drag model of Grace and coefficient of 4, and lift coefficient of 0.001 can be achieved. The research results suggest that gas-fluid two-phase flow in large flotation cell can be well simulated using computational fluid dynamics method.
基金Project(10872219) supported by the National Natural Science Foundation of China
文摘The finite element method was used to solve fluid dynamic interaction problems between the crust and mantle of the Earth. To consider different mechanical behaviours, the lithosphere consisting of the crust and upper mantle was simulated as fluid-saturated porous rocks, while the upper aesthenospheric part of the mantle was simulated as viscous fluids. Since the whole lithosphere was computationally simulated, the dynamic interaction between the crust and the upper mantle was appropriately considered. In particular, the mixing of mantle fluids and crustal fluids was simulated in the corresponding computational model. The related computational simulation results from an example problem demonstrate that the mantle fluids can flow into the crust and mix with the crustal fluids due to the resulting convective flows in the crust-mantle system. Likewise, the crustal fluids can also flow into the upper mantle and mix with the mantle fluids. This kind of fluids mixing and exchange is very important to the better understanding of the governing processes that control the ore body formation and mineralization in the upper crust of the Earth.
基金Funded by National Science Foundation(No.50778415 and No.50878177)
文摘We investigated the effect of supply air rate and temperature on formaldehyde emission characteristics in an environment chamber.A three-dimensional computational fluid dynamics(CFD) chamber model for simulating formaldehyde emission in twelve different cases was developed for obtaining formaldehyde concentration by the area-weighted average method.Laboratory experiments were conducted in an environment chamber to validate the simulation results of twelve different cases and the formaldehyde concentration was measured by continuous sampling.The results show that there was good agreement between the model prediction and the experimental values within 4.3 difference for each case.The CFD simulation results varied in the range from 0.21 mg/m3 to 0.94 mg/m3,and the measuring results in the range from 0.17 mg/m3 to 0.87 mg/m3.The variation trend of formaldehyde concentration with supply air rate and temperature variation for CFD simulation and experiment measuring was consistent.With the existence of steady formaldehyde emission sources,formaldehyde concentration generally increased with the increase of temperature,and it decreased with the increase of air supply rate.We also provided some reasonable suggestions to reduce formaldehyde concentration and to improve indoor air quality for newly decorated rooms.
基金supported by the Natural Science Foundation of China(Nos.61527811 and 61701435)the Key Research and Development Program of Zhejiang Province(No.2020C03016)+1 种基金the Zhejiang Provincial Natural Science Foundation of China(No.LY17H180003)the Medical Health Science and Technology Project of Zhejiang Provincial Health Commission(No.2020RC094),China。
文摘The dysfunction of coronary microcirculation is an important cause of coronary artery disease(CAD).The index of microcirculatory resistance(IMR)is a quantitative evaluation of coronary microcirculatory function,which provides a significant reference for the prediction,diagnosis,treatment,and prognosis of CAD.IMR also plays a key role in investigating the interaction between epicardial and microcirculatory dysfunctions,and is closely associated with coronary hemodynamic parameters such as flow rate,distal coronary pressure,and aortic pressure,which have been widely applied in computational studies of CAD.However,there is currently a lack of consensus across studies on the normal and pathological ranges of IMR.The relationships between IMR and coronary hemodynamic parameters have not been accurately quantified,which limits the application of IMR in computational CAD studies.In this paper,we discuss the research gaps between IMR and its potential applications in the computational simulation of CAD.Computational simulation based on the combination of IMR and other hemodynamic parameters is a promising technology to improve the diagnosis and guide clinical trials of CAD.
基金supported by the National Natural Science Foundation of China(Nos.21502062,21272091 and 21472063)Hubei Provincial Department of Education(No.Q20102606)+3 种基金Xiangyang Science and Technology Bureau(No.2010GG1B33)Structural Biomedicine and Pharmacochemistry of Hubei University of Arts and Sciencethe support from the Russian Foundation for Basic Research(No.18-29-04047)the Tomsk Polytechnic University Competitiveness Enhancement Program grant(No.VIU-195/2018)
文摘The cytochrome bc1complex(the bc1complex or complex Ⅲ) is an attractive target for the discovery of numerous pharmaceuticals and pesticides. In order to identify new lead structures for this target, a new series of molecules, N-(4-aryloxyphenyl)phthalimides, were designed and synthesized in a straightforward manner. Our design strategy was to introduce a 4-aryloxyphenyl group, a fragment which exhibited promising bc1complex-inhibiting properties, into the aryl group of the valuable N-arylphthalimide backbone. Afterward, the biochemical evaluation of the newly synthesized compounds was carried out,and the results implied that several compounds demonstrated good activities against succinatecytochrome reductase(SCR, a mixture of mitochondrial complex Ⅱ and the bc1complex). Further studies confirmed that 3e’, a representative compound in this paper, was identified as an inhibitor of the bc1complex. Furthermore, computational simulations were also performed to better understand binding of 3e’ to the enzyme complex, which indicated that 3e’ should bind to the Qosite of the bc1complex.Consequently, we harbor the idea that this paper can provide a solid platform for synthesis and discovery of other bc1complex inhibitors.
基金financially supported by the National Natural Science Foundation of China(Nos.21838003,91834301 and 21878092)the Shanghai Scientific and Technological Innovation Project(No.18JC1410600)+2 种基金the Social Development Program of Shanghai(Nos.17DZ1200900 and 18DZ2252400)the Innovation Program of Shanghai Municipal Education Commissionthe Fundamental Research Funds for the Central Universities(No.222201718002)。
文摘The suspension characteristics of ultrafine powder slurry in the stirred vessel were simulated by using computational fluid dynamics.The results show that the Rushton disk turbine impeller is more conducive to maintaining suspended homogeneity and circulation of slurry compared with the pitch blade turbine pumping up impeller and the pitch blade turbine pumping down impeller.And the increase in stirring speed enhances turbulent fluctuation and anisotropic velocity of the fluid at the cost of more power consumption,which improves dispersibility and suspensibility of the particles.Meanwhile,the change of impeller clearance has a weak influence on the flow pattern,and the impeller clearance of 0.32T(T is the diameter of the bottom of the reactor)can achieve better dispersivity and suspensibility of the particles with lower power consumption and larger axial velocity.The experiments of surface coating modification of ultrafine titanium dioxide(TiO2)were carried out under the same conditions for those of the simulation system.The surface film morphology and photocatalytic properties of the modified TiO2 were analyzed,and the obtained data are well consistent with the simulation results.
文摘In this work, we first investigated the hemodynamic parameters in the case of a normal aortic arch anatomy and in the case of aortic coarctation anatomy, both generated by using CFX-ICEM-ANSYS simulations. Then, we compared these results with those obtained for a proposed model without and with aortic coarctation, while introducing a real tridimensional magnetic resonance imaging geometry in the simulation process. The conclusion is that our proposed model reproduces, with a high agreement, the real case obtained from imaging data.
基金support from the National Natural Science Foundation of China(No.22172055)the Natural Science Foundation of Guangdong Province(Nos.2023B1515040026,2022A1515011892)the Basic and Applied Basic Research Program of Guangzhou City(Nos.202002030083,202102080443)is gratefully acknowledged.
文摘The self-assembled structures of H_(3) BDA molecule with multiple meta-dicarboxylic groups and their stim-ulus responses to the vip molecules(COR and T4PT)are thoroughly investigated by scanning tunneling microscopy(STM).STM observations display that two kinds of nanostructures are fabricated by H3 BDA molecules through intermolecular hydrogen bonds,in which a linear structure is formed at a higher con-centration and a flower-like structure is obtained at a lower concentration.After the addition of COR and T4PT,H_(3) BDA appears different responsiveness resulting in different co-assembled structures,respectively.The linear structure is regulated into a flower-like structure by COR and COR molecules are trapped in the cavities.When the pyridine derivative(T4PT)is introduced,a new bicomponent porous structure emerges via the hydrogen bond formed between the carboxyl group and the pyridine.Furthermore,the deposition of additional COR to the H_(3) BDA/T4PT system results in the breakdown of the porous structure and the generation of H_(3) BDA/COR host-vip system.Combined with density functional theory(DFT)calculations and molecular dynamics(MD)simulations,the transformation phenomenon of bi-component nanostruc-ture induced by vip molecules is formulated.The results are expected to understand the modification effect of vip molecules on the host network,which is of great significance for the design and construc-tion of multi-component nanostructures and crystal engineering.
文摘Fixed-bed reactors are generally considered the optimal choice for numerous multi-phase catalytic reactions due to their excellent performance and stability.However,conventional fixed beds often encounter challenges related to inadequate mass transfer and a high pressure drop caused by the non-uniform void fraction distribution.To enhance the overall performance of fixed beds,the impact of different packing configurations on performance was investigated.Experimental and simulation methods were used to investigate the fluid flow and mass transfer performances of various packed beds under different flow rates.It was found that structured beds exhibited a significantly lower pressure drop per unit length than conventional packed beds.Furthermore,the packing configurations had a critical role in improving the overall performance of fixed beds.Specifically,structured packed beds,particularly the H-2 packing configuration,effectively reduced the pressure drop per unit length and improved the mass transfer efficiency.The H-2 packing configuration consisted of two parallel strips of particles in each layer,with strips arranged perpendicularly between adjacent layers,and the spacing between the strips varied from layer to layer.
文摘The design of three-dimensional printing based conformal cooling channels(CCCs)in injection molding holds great significance.Compared to CCCs,conformal cooling(CC)cavity solutions show promise in delivering enhanced cooling performance for plastic products,although they have been underexplored.In this research,CC cavity is designed within the mold geometry,reinforced by body-centered cubic(BCC)lattice structures to enhance mechanical strength.Three distinct BCC lattice variations have been integrated into the CC cavity:the BCC structure,BCC with cubes,and BCC with pillars.The thermal performances of the BCC lattice-added CC cavity are assessed numerically after experimental validation.To provide feasible solutions from viewpoints of thermal performances,various BCC lattice structure thicknesses are analyzed in the range of 0.8–1.2mm.Thermal simulation outcomes reveal that thicker lattice structures enhance mechanical strength but simultaneously lead to an increase in cooling time.Upon examining all the proposed CC cavity solutions supported by BCC,the cooling times range from 2.2 to 4 s,resulting in a reduction of 38.6%to 66.1%when compared to conventional straightdrilled channels.In contrast to CCCs,CC cavities have the potential to decrease the maximum temperature nonuniformity from 8.5 to 6 K.Nevertheless,the presence of lattice structures in CC cavity solutions results in an elevated pressure drop,reaching 2.8MPa,whereas the results for CCCs remain below2.1MPa.
基金supported by Science and Technology Projects of Gansu,China(No.22ZD6GA014).
文摘The structure of the concave-convex plates has proven to be crucial in optimizing the internal flow characteristics of the electrolyzer for hydrogen production.This paper investigates the impact of the gradual expansion angle of the inlet channel on the internal flow field of alkaline electrolyzers.The flow distribution characteristics of concave-convex plates with different inlet angle structures in the electrolytic cell is discussed.Besides,the system with internal heat source is studied.The results indicate that a moderate gradual expansion angle is beneficial for enhancing fluid uniformity.However,an excessively large gradual expansion angle may lead to adverse reflux phenomena,reducing the overall performance of the electrolytic cell.
基金The National Key Technology R&D Program of China during the11th Five-Year Plan Period(No.2006BAJ04A13,2006BAJ04B04,2006BAJ02A08,2006BAJ02A05,2006BAJ04A05)the Excellent Youth Teachers Program of Ministry of Education of China(No.2007-209).
文摘The relationship between the site selection of a hilly terrain and the natural ventilation of the Dangdamen building complex,which is a traditional folk house,is revealed by a computational fluid dynamics（CFD）simulation.The wind press and speed distributions around the building in four cases with different weather conditions and topographies are simulated.The simulation results show that a hill can reduce the absolute values of the wind pressure at the windward and leeward sides of the building.The encouraging effect of the patio on the natural ventilation in a terrain with a hill is greater than that without a hill.The same situation occurs when comparing the patio effects between summer and winter.The wind speed around the building can be reduced by the hill as it is an obstacle and the degrees of the influence of the hill in summer and in winter are quite different because of different wind directions.The analysis results show that this kind of site selection,with the hill to the north,is a suitable way to settle the conflict of the natural ventilation requirements in summer and in winter under subtropical climate conditions,especially in houses with patios.
基金Project(51405389)supported by the National Natural Science Foundation of ChinaProject(2014003)supported by the Shanghai Key Laboratory of Digital Manufacture for Thin-walled Structures,China+1 种基金Project(3102015ZY024)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(108-QP-2014)supported by the Research Fund of the State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,China
文摘The flow distribution in quench tank for heat treatment of A357 alloy large complicated components was simulated using FLUENT computational fluid dynamics（CFD） software.The flow velocity and the uniformity of flow field in two types of quench tanks（with or without agitation system） were calculated.The results show that the flow field in the quench tank without agitation system has not evident regularity.While as for the quench tank with agitation system,the flow fields in different parameters have certain regularity.The agitation tanks have a distinct advantage over the system without agitation.Proper process parameters were also obtained.Finally,the tank model established in this work was testified by an example from publication.This model with high accuracy is able to optimize the tank structures and can be helpful for industrial production and theoretical investigation in the fields of heat treatment of large complicated components.
基金China Scholarship Council Postgraduate Scholarship Program(No.2007U20027)the National Natural Science Foundation of China(No.50876020)the National Key Technology R&D Program of China during the 11th Five-Year Plan Period(No.2008BAJ12B02)
文摘An open-source computational fluid dynamics（CFD）code named OpenFOAM is used to validate the flow field characteristics（flow patterns and pressure drop）around a single cylinder.Results show that OpenFOAM is suitable for simulating the low Reynolds number flow and Shaw＇s analytical expression is one of the solutions to Stokes＇ paradox.Experiments are performed on fibrous media and OpenFOAM simulation is carried out using the Tronville-Rivers two-dimensional random fiber model in terms of the characteristics of pressure drop.It is shown that the Kuwabara model predicts the pressure drop of fibrous filter media more accurately than the Happel model,and the experimental pressure drop is between simulated pressure drops with both non-slip and full-slip boundaries on fiber surfaces.
基金financially supported by the National Natural Science Foundation of China(Nos.52071117 and 51771063)the Heilongjiang Provincial Science Fund for Distinguished Young Scholars(No.JQ2021E002)。
文摘Diamond/metal composites are widely used in aerospace and electronic packaging fields due to their outstanding high thermal conductivity and low expansion.However,the difference in chemical properties leads to interface incompatibility between diamond and metal,which has a considerable impact on the performance of the composites.To improve the interface compatibility between diamond and metal,it is necessary to modify the interface of composites.This paper reviews the experimental research on interface modification and the application of computational simulation in diamond/metal composites.Combining computational simulation with experimental methods is a promising way to promote diamond/metal composite interface modification research.
