Gas-liquid two-phase flow in fractal porous media is pivotal for engineering applications,yet it remains challenging to be accurately characterized due to complex microstructure-flow interactions.This study establishe...Gas-liquid two-phase flow in fractal porous media is pivotal for engineering applications,yet it remains challenging to be accurately characterized due to complex microstructure-flow interactions.This study establishes a pore-scale numerical framework integratingMonte Carlo-generated fractal porousmedia with Volume of Fluid(VOF)simulations to unravel the coupling among pore distribution characterized by fractal dimension(Df),flow dynamics,and displacement efficiency.A pore-scale model based on the computed tomography(CT)microstructure of Berea sandstone is established,and the simulation results are compared with experimental data.Good agreement is found in phase distribution,breakthrough behavior,and flow path morphology,confirming the reliability of the numerical simulation method.Ten fractal porous media models with Df ranging from 1.25~1.7 were constructed using a Monte-Carlo approach.The gas-liquid two-phase flow dynamics was characterized using the VOF solver across gas injection rates of 0.05-5m/s,inwhich the time-resolved two-phase distribution patternswere systematically recorded.The results reveal that smaller fractal dimensions(Df=1.25~1.45)accelerate fingering breakthrough(peak velocity is 1.73 m/s at Df=1.45)due to a bimodal pore size distribution dominated by narrow channels.Increasing Df amplifies vorticity generation by about 3 times(eddy viscosity is 0.033 Pa⋅s at Df=1.7)through reduced interfacial curvature,while tortuosity-driven pressure differentials transition from sharp increases(0.4~6.3 Pa at Df=1.25~1.3)to inertial plateaus(4.8 Pa at Df=1.7).A nonlinear increase in equilibrium gas volume fraction(fav=0.692 at Df=1.7)emerges from residual gas saturation and turbulence-enhanced dispersion.This behavior is further modulated by flow velocity,with fav peaking at 0.72 under capillary-dominated conditions(0.05 m/s),but decreasing to 0.65 in the inertial regime(0.5 m/s).The work quantitatively links fractal topology to multiphase flow regimes,demonstrating the critical role of Df in governing preferential pathways,energy dissipation,and phase distribution.展开更多
Polymer flooding is an important means of improving oil recovery and is widely used in Daqing,Xinjiang,and Shengli oilfields,China.Different from conventional injection media such as water and gas,viscoelastic polymer...Polymer flooding is an important means of improving oil recovery and is widely used in Daqing,Xinjiang,and Shengli oilfields,China.Different from conventional injection media such as water and gas,viscoelastic polymer solutions exhibit non-Newtonian and nonlinear flow behavior including shear thinning and shear thickening,polymer convection,diffusion,adsorption,retention,inaccessible pore volume,and reduced effective permeability.However,available well test model of polymer flooding wells generally simplifies these characteristics on pressure transient response,which may lead to inaccurate results.This work proposes a novel two-phase numerical well test model to better describe the polymer viscoelasticity and nonlinear flow behavior.Different influence factors that related to near-well blockage during polymer flooding process,including the degree of blockage(inner zone permeability),the extent of blockage(composite radius),and polymer flooding front radius are explored to investigate these impacts on bottom hole pressure responses.Results show that polymer viscoelasticity has a significant impact on the transitional flow segment of type curves,and the effects of near-well formation blockage and polymer concentration distribution on well test curves are very similar.Thus,to accurately interpret the degree of near-well blockage in injection wells,it is essential to first eliminate the influence of polymer viscoelasticity.Finally,a field case is comprehensively analyzed and discussed to illustrate the applicability of the proposed model.展开更多
In multiphase pumps transporting gas-liquid two-phase flows,the high-speed rotation of the impeller induces complex deformations in bubble shapes within the flow domain,making the prediction of gasliquid two-phase dra...In multiphase pumps transporting gas-liquid two-phase flows,the high-speed rotation of the impeller induces complex deformations in bubble shapes within the flow domain,making the prediction of gasliquid two-phase drag forces highly challenging in numerical simulations.To achieve precise prediction of the drag forces on irregular bubbles within multiphase pumps,this study modifies the existing bubble drag force model and applies the revised model to the prediction of gas-liquid two-phase flow within multiphase pumps.The research findings indicate that the modified drag force model significantly enhances the accuracy of predicting flow characteristics within the pump,particularly under high gas volume fraction conditions.The simulation results for gas phase distribution and vorticity exhibit strong agreement with experimental data.The modified drag model better captures the accumulation of the gas phase at the suction side of the impeller outlet.It also accurately predicts the vortex characteristics induced by bubble backflow from the trailing edges of the diffuser.Additionally,the adjustment of the drag coefficient enhances the model’s ability to represent local flow field characteristics,thereby optimizing the performance simulation methods of multiphase pumps.Compared to traditional drag force models,the modified model reduces prediction errors in head and efficiency by 36.4%and 27.5%,respectively.These results provide important theoretical foundations and model support for improving the accuracy of gas-liquid two-phase flow simulations and optimizing the design of multiphase pumps under high gas volume fraction conditions.展开更多
A“water”accelerated metal-free catalytic system has been discovered for the Mukaiyama-aldol reaction.The system involves the use of B(C_(6)F_(5))_(3) as a catalyst,which is water-tolerant and able to activate the ca...A“water”accelerated metal-free catalytic system has been discovered for the Mukaiyama-aldol reaction.The system involves the use of B(C_(6)F_(5))_(3) as a catalyst,which is water-tolerant and able to activate the carbonyl group through a hydrogen bonding network generated by the catalyst.This activation method allows the reactions to be performed with very low catalyst loading,as low as 0.5 mol%.The scope of substrates is broad and a wide variety of functional groups are well tolerated.Diverse aliphatic aldehydes,aromatic aldehydes,unsaturated aldehydes and aromatic ketones coupled with silyl enol ethers/silyl ketone acetals to generate their correspondingβ-hydroxy carbonyl compounds in moderate to good yields.This discovery represents a significant advancement in the field of organic synthesis,as it provides a new,practical and sustainable solution for carbon-carbon bond formation in water.展开更多
Dominant phase during hot deformation in the two-phase region of Zr-2.5Nb-0.5Cu （ZNC） alloy was studied using activation energy calculation of individual phases. Thermo-mechanical compression tests were performed on...Dominant phase during hot deformation in the two-phase region of Zr-2.5Nb-0.5Cu （ZNC） alloy was studied using activation energy calculation of individual phases. Thermo-mechanical compression tests were performed on a two-phase ZNC alloy in the temperature range of 700-925 ℃ and strain rate range of 10-2-10 s-l, Flow stress data of the single phase were extrapolated in the two-phase range to calculate flow stress data of individual phases. Activation energies of individual phases were then calculated using calculated flow stress data in the two-phase range, Comparison of activation energies revealed that a phase is the dominant phase （deformation controlling phase） in the two-phase range. Constitutive equations were also developed on the basis of the deformation temperature range （or according to phases present） using a sine-hyperbolic type constitutive equation. The statistical analysis revealed that the constitutive equation developed for a particular phase showed good agreement with the experimental results in terms of correlation coefficient （R） and average absolute relative error （AARE）.展开更多
Biot-flow and squirt-flow are the two most important fluid flow mechanisms in porous media containing fluids. Based on the BISQ （Biot-Squirt） model where the two mechanisms are treated simultaneously, the elastic wa...Biot-flow and squirt-flow are the two most important fluid flow mechanisms in porous media containing fluids. Based on the BISQ （Biot-Squirt） model where the two mechanisms are treated simultaneously, the elastic wave-field simulation in the porous medium is limited to two-dimensions and two-components （2D2C） or two-dimensions and three-components （2D3C）. There is no previous report on wave simulation in three- dimensions and three-components. Only through three dimensional numerical simulations can we have an overall understanding of wave field coupling relations and the spatial distribution characteristics between the solid and fluid phases in the dual-phase anisotropic medium. In this paper, based on the BISQ equation, we present elastic wave propagation in a three dimensional dual-phase anisotropic medium simulated by the staggered-grid high-order finite-difference method. We analyze the resulting wave fields and show that the results are an improvement.展开更多
To improve the accuracy of the conventional finite-difference method, finitedifference numerical modeling methods of any even-order accuracy are recommended. We introduce any even-order accuracy difference schemes of ...To improve the accuracy of the conventional finite-difference method, finitedifference numerical modeling methods of any even-order accuracy are recommended. We introduce any even-order accuracy difference schemes of any-order derivatives derived from Taylor series expansion. Then, a finite-difference numerical modeling method with any evenorder accuracy is utilized to simulate seismic wave propagation in two-phase anisotropic media. Results indicate that modeling accuracy improves with the increase of difference accuracy order number. It is essential to find the optimal order number, grid size, and time step to balance modeling precision and computational complexity. Four kinds of waves, static mode in the source point, SV wave cusps, reflection and transmission waves are observed in two-phase anisotropic media through modeling.展开更多
AVO forward modeling is based on two-phase medium theory and is considered an effective method for describing reservoir rocks and fluids. However, the method depends on the input matrix mineral bulk modulus and the ra...AVO forward modeling is based on two-phase medium theory and is considered an effective method for describing reservoir rocks and fluids. However, the method depends on the input matrix mineral bulk modulus and the rationality of the two-phase medium model. We used the matrix mineral bulk modulus inversion method and multiple constraints to obtain a two-phase medium model with physical meaning. The proposed method guarantees the reliability of the obtained AVO characteristicsin two-phase media. By the comparative analysis of different lithology of the core sample, the advantages and accuracy of the inversion method can be illustrated. Also, the inversion method can be applied in LH area, and the AVO characteristics can be obtained when the porosity, fluid saturation, and other important lithology parameters are changed. In particular, the reflection coefficient amplitude difference between the fast P wave and S wave as a function of porosity at the same incidence angle, and the difference in the incidence angle threshold can be used to decipher porosity.展开更多
A second-order moment two-phase turbulence model for simulating dense gas-particle flows （USM-Θ model）, combining the unified second-order moment twophase turbulence model for dilute gas-particle flows with the kin...A second-order moment two-phase turbulence model for simulating dense gas-particle flows （USM-Θ model）, combining the unified second-order moment twophase turbulence model for dilute gas-particle flows with the kinetic theory of particle collision, is proposed. The interaction between gas and particle turbulence is simulated using the transport equation of two-phase velocity correlation with a two-time-scale dissipation closure. The proposed model is applied to simulate dense gas-particle flows in a horizontal channel and a downer. Simulation results and their comparison with experimental results show that the model accounting for both anisotropic particle turbulence and particle-particle collision is obviously better than models accounting for only particle turbulence or only particle-particle collision. The USM-Θ model is also better than the k-ε-kp-Θ model and the k-ε-kp-εp-Θ model in that the first model can simulate the redistribution of anisotropic particle Reynolds stress components due to inter-particle collision, whereas the second and third models cannot.展开更多
To investigate the flow behavior of 2219 Al alloy during warm deformation,the thermal compression test was conducted in the temperature range of 483-573 K and the strain rate range of 0.001-5 s^(-1) on a Gleeble-3500 ...To investigate the flow behavior of 2219 Al alloy during warm deformation,the thermal compression test was conducted in the temperature range of 483-573 K and the strain rate range of 0.001-5 s^(-1) on a Gleeble-3500 thermomechanical simulation unit.The true stress-true strain curves obtained showed that the flow stress increased with the decrease in temperature and/or the increase in strain rate and the softening mechanism primarily proceeded via dynamic recovery.The modification on the conventional Arrhenius-type constitutive model approach was made,the material variables and activation energy were determined to be dependent on the deformation parameters.The modified flow stresses were found to be in close agreement with the experimental values.Furthermore,the activation energy obtained under different deformation conditions showed that it decreased with the rise in temperature and/or strain rate,and was also affected by the coupled effect of strain and strain rate.展开更多
The 4340 steel is extensively utilized in several industries including automotive and aerospace for manufac- turing a large number of structural components. Due to the importance of thermo-mechanical processing in the...The 4340 steel is extensively utilized in several industries including automotive and aerospace for manufac- turing a large number of structural components. Due to the importance of thermo-mechanical processing in the pro- duction of steels, the dynamic recrystallization （DRX） characteristics of 4340 steel were investigated. Namely, hot compression tests on 4340 steel have been performed in a temperature range of 900-- 1200 ℃ and a strain rate range of 0.01--1 s-1 and the strain of up to 0.9. The resulting flow stress curves show the occurrence of dynamic recrys- tallization. The flow stress values decrease with the increase of deformation temperature and the decrease of strain rate. The microstrueture of 4340 steel after deformation has been studied and it is suggested that the evolution of DRX grain structures can be accompanied by considerable migration of grain boundaries. The constitutive equations were developed to model the hot deformation behavior. Finally based on the classical stress-dislocation relations and the kinematics of the dynamic recrystallization; the flow stress constitutive equations for the dynamic recovery period and dynamic reerystallization period were derived for 4340 steel, respectively. The validity of the model was demon- strated by demonstrating the experimental data with the numerical results with reasonable agreement.展开更多
The volume fraction of the solid and liquid phase of debris flows,which evolves simultaneously across terrains,largely determines the dynamic property of debris flows.The entrainment process significantly influences t...The volume fraction of the solid and liquid phase of debris flows,which evolves simultaneously across terrains,largely determines the dynamic property of debris flows.The entrainment process significantly influences the amplitude of the volume fraction.In this paper,we present a depth-averaged two-phase debris-flow model describing the simultaneous evolution of the phase velocity and depth,the solid and fluid volume fractions and the bed morphological evolution.The model employs the Mohr–Coulomb plasticity for the solid stress,and the fluid stress is modeled as a Newtonian viscous stress.The interfacial momentum transfer includes viscous drag and buoyancy.A new extended entrainment rate formula that satisfies the boundary momentum jump condition(Iverson and Ouyang,2015)is presented.In this formula,the basal traction stress is a function of the solid volume fraction and can take advantage of both the Coulomb and velocity-dependent friction models.A finite volume method using Roe’s Riemann approximation is suggested to solve the equations.Three computational cases are conducted and compared with experiments or previous results.The results show that the current computational model and framework are robust and suitable for capturing the characteristics of debris flows.展开更多
AIM： To establish a highly reproducible animal model of acute liver failure （ALF）, for assessing the effect of bioartificial liver support system （BALSS）. METHODS： A two-phase complete liver devascularization pr...AIM： To establish a highly reproducible animal model of acute liver failure （ALF）, for assessing the effect of bioartificial liver support system （BALSS）. METHODS： A two-phase complete liver devascularization procedure was performed in eight Ioco-hybrid pigs. Blood biochemical index and liver biopsy were studied every 2 h after surgery, and survival time was recorded. The BALSS constructed with high volume recirculating technique was a hollow fiber circulating system consisting of a hepatocyte reactor-hollow fiber module inoculated with microcarrieradhering hepatocytes, and a double pump, heparinized, thermostabilized, micro-capsulized activated carbonadsorbing plasmapheresis system. Twelve pigs undergoing two-phase surgery were randomized into： control group （perfused without hepatocytes, n = 6） and treatment group （perfused with hepatocytes, n = 6）. Intergroup liver biochemical indexes, survival time, and liver pathological changes were analyzed at regular intervals. RESULTS： Two-phase surgery was performed in all the experimental pigs, and there was no obvious difference between their biochemical indexes. After 3 h of phase II surgery, ammonia （Amm） increased to （269＋37）μmol/L. After 5 h of the surgery, fibrinogen （Fib） decreased to （1.5±0.2） g/L. After 7 h of the surgery, ALT, AST, Tbil and PT were （7.6±1.8） nka/L, （40±5） nka/L, （55±8）μmol/L and （17.5±1.7） nka/L respectively. After 9 h of surgery, ALB and Cr were （27±4） g/L and （87±9）μmol/L. After 13 h of surgery, BUN was （3.5±0.9） μmol/L. All the above values were different from those determined before surgery. Survival time of pigs averaged 13.5±1.4 h. ALF pigs in the other group were treated with BALSS. The comparison analysis between the treated and control animals showed the changes of Tbil, PT, AIb, BUN, Cr, Fib, and Amm （P〈0.01）, but there was no change of ALT and AST. The survival time was statistically different （P〈0.01）, and there was no significant difference in histological changes.CONCLUSION： The porcine ALF model established by two-phase devascularized surgery is valid and reproducible. The hollow fiber BALSS can meet the needs of life support and is effective in treating ALF.展开更多
Clayey-silt natural gas hydrate reservoirs in the South China Sea exhibit loose and unconsolidated structures, heterogeneous pore structures, high clay mineral contents, and strong hydrophilicity. These characteristic...Clayey-silt natural gas hydrate reservoirs in the South China Sea exhibit loose and unconsolidated structures, heterogeneous pore structures, high clay mineral contents, and strong hydrophilicity. These characteristics complicate the gas-water two-phase flow process in porous media following hydrate decomposition, posing challenges for efficient development. This study examines the transport response of clayey-silt reservoir samples from the Shenhu area using gas-water two-phase flow experiments and CT scanning to explore changes in pore structure, gas-water distribution, and relative permeability under varying flow conditions. The results indicate that pore heterogeneity significantly influences flow characteristics. Gas preferentially displaces water in larger pores, forming fracture-like pores, which serve as preferential flow channels for gas migration. The preferential flow channels enhance gas-phase permeability up to 19 times that of the water phase when fluid pressures exceed total stresses. However,small pores retain liquid, leading to a high residual water saturation of 0.561. CT imaging reveals that these hydro-fractures improve gas permeability but also confine gas flow to specific channels. Pore network analysis shows that gas injection expands the pore-throat network, enhancing connectivity and forming fracture-like pores. Residual water remains trapped in smaller pores and throats, while structural changes, including new fractures, improve gas flow pathways and overall connectivity. Relative permeability curves demonstrate a narrow gas-water cocurrent-flow zone, a right-shifted iso-permeability point and high reservoir capillary pressure, indicating a strong "water-blocking" effect. The findings suggest that optimizing reservoir stimulation techniques to enhance fracture formation, reduce residual water saturation, and improve gas flow capacity is critical for efficient hydrate reservoir development.展开更多
The two-phase flow models are commonly used in industrial applications, such as nuclear, power, chemical-process, oil-and-gas, cryogenics, bio-medical, micro-technology and so on. This is a survey paper on the study o...The two-phase flow models are commonly used in industrial applications, such as nuclear, power, chemical-process, oil-and-gas, cryogenics, bio-medical, micro-technology and so on. This is a survey paper on the study of compressible nonconservative two-fluid model, drift-flux model and viscous liquid-gas two-phase flow model. We give the research developments of these three two-phase flow models, respectively. In the last part, we give some open problems about the above models.展开更多
A full second-order moment (FSM) model and an algebraic stress (ASM) two-phase turbulence modelare proposed and applied to predict turbulent bubble-liquid flows in a 2D rectangular bubble column. Predictiongives the b...A full second-order moment (FSM) model and an algebraic stress (ASM) two-phase turbulence modelare proposed and applied to predict turbulent bubble-liquid flows in a 2D rectangular bubble column. Predictiongives the bubble and liquid velocities, bubble volume fraction, bubble and liquid Reynolds stresses and bubble-liquidvelocity correlation. For predicted two-phase velocities and bubble volume fraction there is only slight differencebetween these two models, and the simulation results using both two models are in good agreement with the particleimage velocimetry (PIV) measurements. Although the predicted two-phase Reynolds stresses using the FSM are insomewhat better agreement with the PIV measurements than those predicted using the ASM, the Reynolds stressespredicted using both two models are in general agreement with the experiments. Therefore, it is suggested to usethe ASM two-phase turbulence model in engineering application for saving the computation time.展开更多
Thermal maturation and petroleum generation modeling of shales is essential for suc- cessful exploration and exploitation of conventional and unconventional oil and gas plays. For basin- wide unconventional resource p...Thermal maturation and petroleum generation modeling of shales is essential for suc- cessful exploration and exploitation of conventional and unconventional oil and gas plays. For basin- wide unconventional resource plays such modeling, when well calibrated with direct maturity meas- urements from wells, can characterize and locate production sweet spots for oil, wet gas and dry gas. The transformation of kerogen to petroleum is associated with many chemical reactions, but models typically focus on first-order reactions with rates determined by the Arrhenius Equation. A miscon- ception has been perpetuated for many years that accurate thermal maturity modeling of vitrinite re- flectance using the Arrhenius Equation and a single activation energy, to derive a time-temperature index （~TTIARa）, as proposed by Wood （1988）, is flawed. This claim was initially made by Sweeney and Burnham （1990） in promoting their ＂EasyRo＂ method, and repeated by others. This paper dem- onstrates through detailed multi-dimensional burial and thermal modeling and direct comparison of the ~TTIARR and ＂EasyRo＂ methods that this is not the case. The ~TTIA^R method not only provides a very useful and sensitive maturity index, it can reproduce the calculated vitrinite reflectance values derived from models based on multiple activation energies （e.g., ＂EasyRo＂）. Through simple expres- sions the ~TTIAaa method can also provide oil and gas transformation factors that can be flexibly scaled and calibrated to match the oil, wet gas and dry gas generation windows. This is achieved in a more-computationally-efficient, flexible and transparent way by the ~TTIARR method than the ＂EasyRo＂ method. Analysis indicates that the ＂EasyRo＂ method, using twenty activation energies and a constant frequency factor, generates reaction rates and transformation factors that do not realisti- cally model observed kerogen behaviour and transformation factors over geologic time scales.展开更多
The growing demand for brilliant smile and tooth whitening has led to the increasing significance of tooth whitening methods.However,the development of tooth whitening materials with high efficiency and safety has bee...The growing demand for brilliant smile and tooth whitening has led to the increasing significance of tooth whitening methods.However,the development of tooth whitening materials with high efficiency and safety has been considered to be an urgent challenge.Here,we report a novel tooth whitening strategy,which overcomes the limitation of conventional methods,shows excellent tooth whitening efficiency and safety,and even exhibits outstanding antibacterial activity.Inspired by stomata and chloroplasts in green leaves,we have developed an integrated two-phase free radical hydrogel(TP-GEL),which integrates solid-phase and liquid-phase free radical functional components fabricated by cold plasma technology.TP-GEL demonstrated safe and ultrafast tooth-whitening effect with or without visible light,which can be more significant than that of 30% H_(2)O_(2),the commonly whitening material in dental clinical practice.More importantly,we also avoid the damage to enamel,such as microhardness,roughness,surface morphology.Benefiting from free radicals,much higher antibacterial properties than commercial products(Chlorhexidine)was obtained.This research provides fundamental design criteria for the development of dual functional oral health care materials with advanced tooth whitening and antibacterial activity.展开更多
The dense solid-phase governing equations for two-phase flows are obtained by using the kinetic theory of gas molecules.Assuming that the solid-phase velocity distributions obey the Maxwell equations,the collision ter...The dense solid-phase governing equations for two-phase flows are obtained by using the kinetic theory of gas molecules.Assuming that the solid-phase velocity distributions obey the Maxwell equations,the collision term for particles under dense two-phase flow conditions is also derived. In comparison with the governing equations of a dilute two-phase flow,the solid-particle's governing equations are developed for a dense turbulent solid-liquid flow by adopting some relevant terms from the dilute two-phase governing equations.Based on Cauchy-Helmholtz theorem and Smagorinsky model, a second-order dynamic sub-grid-scale(SGS)model,in which the sub-grid-scale stress is a function of both the strain-rate tensor and the rotation-rate tensor,is proposed to model the two-phase governing equations by applying dimension analyses.Applying the SIMPLEC algorithm and staggering grid system to the two-phase discretized governing equations and employing the slip boundary conditions on the walls,the velocity and pressure fields,and the volumetric concentration are calculated.The simulation results are in a fairly good agreement with experimental data in two operating cases in a conduit with a rectangular cross-section and these comparisons imply that these models are practical.展开更多
In this work, we obtain the global existence and uniqueness of classical solu-tions to a viscous liquid-gas two-phase model with mass-dependent viscosity and vacuum in one dimension, where the initial vacuum is allowe...In this work, we obtain the global existence and uniqueness of classical solu-tions to a viscous liquid-gas two-phase model with mass-dependent viscosity and vacuum in one dimension, where the initial vacuum is allowed. We get the upper and lower bounds of gas and liquid masses n and m by the continuity methods which we use to study the compressible Navier-Stokes equations.展开更多
基金funded by the National Key R&D Program of China,China(Grant No.2023YFB4005500)National Natural Science Foundation of China,China(Grant Nos.52379113 and 52379114).
文摘Gas-liquid two-phase flow in fractal porous media is pivotal for engineering applications,yet it remains challenging to be accurately characterized due to complex microstructure-flow interactions.This study establishes a pore-scale numerical framework integratingMonte Carlo-generated fractal porousmedia with Volume of Fluid(VOF)simulations to unravel the coupling among pore distribution characterized by fractal dimension(Df),flow dynamics,and displacement efficiency.A pore-scale model based on the computed tomography(CT)microstructure of Berea sandstone is established,and the simulation results are compared with experimental data.Good agreement is found in phase distribution,breakthrough behavior,and flow path morphology,confirming the reliability of the numerical simulation method.Ten fractal porous media models with Df ranging from 1.25~1.7 were constructed using a Monte-Carlo approach.The gas-liquid two-phase flow dynamics was characterized using the VOF solver across gas injection rates of 0.05-5m/s,inwhich the time-resolved two-phase distribution patternswere systematically recorded.The results reveal that smaller fractal dimensions(Df=1.25~1.45)accelerate fingering breakthrough(peak velocity is 1.73 m/s at Df=1.45)due to a bimodal pore size distribution dominated by narrow channels.Increasing Df amplifies vorticity generation by about 3 times(eddy viscosity is 0.033 Pa⋅s at Df=1.7)through reduced interfacial curvature,while tortuosity-driven pressure differentials transition from sharp increases(0.4~6.3 Pa at Df=1.25~1.3)to inertial plateaus(4.8 Pa at Df=1.7).A nonlinear increase in equilibrium gas volume fraction(fav=0.692 at Df=1.7)emerges from residual gas saturation and turbulence-enhanced dispersion.This behavior is further modulated by flow velocity,with fav peaking at 0.72 under capillary-dominated conditions(0.05 m/s),but decreasing to 0.65 in the inertial regime(0.5 m/s).The work quantitatively links fractal topology to multiphase flow regimes,demonstrating the critical role of Df in governing preferential pathways,energy dissipation,and phase distribution.
基金supported by the National Natural Science Foundation of China(52104049)the Young Elite Scientist Sponsorship Program by Beijing Association for Science and Technology(BYESS2023262)。
文摘Polymer flooding is an important means of improving oil recovery and is widely used in Daqing,Xinjiang,and Shengli oilfields,China.Different from conventional injection media such as water and gas,viscoelastic polymer solutions exhibit non-Newtonian and nonlinear flow behavior including shear thinning and shear thickening,polymer convection,diffusion,adsorption,retention,inaccessible pore volume,and reduced effective permeability.However,available well test model of polymer flooding wells generally simplifies these characteristics on pressure transient response,which may lead to inaccurate results.This work proposes a novel two-phase numerical well test model to better describe the polymer viscoelasticity and nonlinear flow behavior.Different influence factors that related to near-well blockage during polymer flooding process,including the degree of blockage(inner zone permeability),the extent of blockage(composite radius),and polymer flooding front radius are explored to investigate these impacts on bottom hole pressure responses.Results show that polymer viscoelasticity has a significant impact on the transitional flow segment of type curves,and the effects of near-well formation blockage and polymer concentration distribution on well test curves are very similar.Thus,to accurately interpret the degree of near-well blockage in injection wells,it is essential to first eliminate the influence of polymer viscoelasticity.Finally,a field case is comprehensively analyzed and discussed to illustrate the applicability of the proposed model.
基金funded by Sichuan Natural Science Foundation Outstanding Youth Science Foundation(No.2024NSFJQ0012)Key project of Regional Innovation and Development Joint Fund of National Natural Science Foundation(No.U23A20669)Sichuan Science and Technology Program(2022ZDZX0041).
文摘In multiphase pumps transporting gas-liquid two-phase flows,the high-speed rotation of the impeller induces complex deformations in bubble shapes within the flow domain,making the prediction of gasliquid two-phase drag forces highly challenging in numerical simulations.To achieve precise prediction of the drag forces on irregular bubbles within multiphase pumps,this study modifies the existing bubble drag force model and applies the revised model to the prediction of gas-liquid two-phase flow within multiphase pumps.The research findings indicate that the modified drag force model significantly enhances the accuracy of predicting flow characteristics within the pump,particularly under high gas volume fraction conditions.The simulation results for gas phase distribution and vorticity exhibit strong agreement with experimental data.The modified drag model better captures the accumulation of the gas phase at the suction side of the impeller outlet.It also accurately predicts the vortex characteristics induced by bubble backflow from the trailing edges of the diffuser.Additionally,the adjustment of the drag coefficient enhances the model’s ability to represent local flow field characteristics,thereby optimizing the performance simulation methods of multiphase pumps.Compared to traditional drag force models,the modified model reduces prediction errors in head and efficiency by 36.4%and 27.5%,respectively.These results provide important theoretical foundations and model support for improving the accuracy of gas-liquid two-phase flow simulations and optimizing the design of multiphase pumps under high gas volume fraction conditions.
基金financial support from the Start-up Grant of Nanjing Tech University(Nos.38274017103,38037037)financial support from Distinguished University Professor grant(Nanyang Technological University)+1 种基金the Agency for Science,Technology and Research(A∗STAR)under its MTC Individual Research Grants(No.M21K2c0114)RIE2025 MTC Programmatic Fund(No.M22K9b0049).
文摘A“water”accelerated metal-free catalytic system has been discovered for the Mukaiyama-aldol reaction.The system involves the use of B(C_(6)F_(5))_(3) as a catalyst,which is water-tolerant and able to activate the carbonyl group through a hydrogen bonding network generated by the catalyst.This activation method allows the reactions to be performed with very low catalyst loading,as low as 0.5 mol%.The scope of substrates is broad and a wide variety of functional groups are well tolerated.Diverse aliphatic aldehydes,aromatic aldehydes,unsaturated aldehydes and aromatic ketones coupled with silyl enol ethers/silyl ketone acetals to generate their correspondingβ-hydroxy carbonyl compounds in moderate to good yields.This discovery represents a significant advancement in the field of organic synthesis,as it provides a new,practical and sustainable solution for carbon-carbon bond formation in water.
基金financial support(Grant No.2011/36/15)from Board of Research in Nuclear Science(BRNS),India
文摘Dominant phase during hot deformation in the two-phase region of Zr-2.5Nb-0.5Cu （ZNC） alloy was studied using activation energy calculation of individual phases. Thermo-mechanical compression tests were performed on a two-phase ZNC alloy in the temperature range of 700-925 ℃ and strain rate range of 10-2-10 s-l, Flow stress data of the single phase were extrapolated in the two-phase range to calculate flow stress data of individual phases. Activation energies of individual phases were then calculated using calculated flow stress data in the two-phase range, Comparison of activation energies revealed that a phase is the dominant phase （deformation controlling phase） in the two-phase range. Constitutive equations were also developed on the basis of the deformation temperature range （or according to phases present） using a sine-hyperbolic type constitutive equation. The statistical analysis revealed that the constitutive equation developed for a particular phase showed good agreement with the experimental results in terms of correlation coefficient （R） and average absolute relative error （AARE）.
基金National Natural Science Foundation (Project number 40604013).
文摘Biot-flow and squirt-flow are the two most important fluid flow mechanisms in porous media containing fluids. Based on the BISQ （Biot-Squirt） model where the two mechanisms are treated simultaneously, the elastic wave-field simulation in the porous medium is limited to two-dimensions and two-components （2D2C） or two-dimensions and three-components （2D3C）. There is no previous report on wave simulation in three- dimensions and three-components. Only through three dimensional numerical simulations can we have an overall understanding of wave field coupling relations and the spatial distribution characteristics between the solid and fluid phases in the dual-phase anisotropic medium. In this paper, based on the BISQ equation, we present elastic wave propagation in a three dimensional dual-phase anisotropic medium simulated by the staggered-grid high-order finite-difference method. We analyze the resulting wave fields and show that the results are an improvement.
文摘To improve the accuracy of the conventional finite-difference method, finitedifference numerical modeling methods of any even-order accuracy are recommended. We introduce any even-order accuracy difference schemes of any-order derivatives derived from Taylor series expansion. Then, a finite-difference numerical modeling method with any evenorder accuracy is utilized to simulate seismic wave propagation in two-phase anisotropic media. Results indicate that modeling accuracy improves with the increase of difference accuracy order number. It is essential to find the optimal order number, grid size, and time step to balance modeling precision and computational complexity. Four kinds of waves, static mode in the source point, SV wave cusps, reflection and transmission waves are observed in two-phase anisotropic media through modeling.
基金supported by the National Natural Science Foundation of China(Grant Nos.41404101,41174114,41274130,and 41404102)
文摘AVO forward modeling is based on two-phase medium theory and is considered an effective method for describing reservoir rocks and fluids. However, the method depends on the input matrix mineral bulk modulus and the rationality of the two-phase medium model. We used the matrix mineral bulk modulus inversion method and multiple constraints to obtain a two-phase medium model with physical meaning. The proposed method guarantees the reliability of the obtained AVO characteristicsin two-phase media. By the comparative analysis of different lithology of the core sample, the advantages and accuracy of the inversion method can be illustrated. Also, the inversion method can be applied in LH area, and the AVO characteristics can be obtained when the porosity, fluid saturation, and other important lithology parameters are changed. In particular, the reflection coefficient amplitude difference between the fast P wave and S wave as a function of porosity at the same incidence angle, and the difference in the incidence angle threshold can be used to decipher porosity.
基金the Special Funds for Major State Basic Research of China(G-1999-0222-08)the National Natural Science Foundation of China(50376004)Ph.D.Program Foundation,Ministry of Education of China(20030007028)
文摘A second-order moment two-phase turbulence model for simulating dense gas-particle flows （USM-Θ model）, combining the unified second-order moment twophase turbulence model for dilute gas-particle flows with the kinetic theory of particle collision, is proposed. The interaction between gas and particle turbulence is simulated using the transport equation of two-phase velocity correlation with a two-time-scale dissipation closure. The proposed model is applied to simulate dense gas-particle flows in a horizontal channel and a downer. Simulation results and their comparison with experimental results show that the model accounting for both anisotropic particle turbulence and particle-particle collision is obviously better than models accounting for only particle turbulence or only particle-particle collision. The USM-Θ model is also better than the k-ε-kp-Θ model and the k-ε-kp-εp-Θ model in that the first model can simulate the redistribution of anisotropic particle Reynolds stress components due to inter-particle collision, whereas the second and third models cannot.
基金Projects(U1637601,51405520,51327902)supported by the National Natural Science Foundation of ChinaProject(ZZYJKT2017-06)supported by State Key Laboratory of High Performance Complex Manufacturing of Central South University,China
文摘To investigate the flow behavior of 2219 Al alloy during warm deformation,the thermal compression test was conducted in the temperature range of 483-573 K and the strain rate range of 0.001-5 s^(-1) on a Gleeble-3500 thermomechanical simulation unit.The true stress-true strain curves obtained showed that the flow stress increased with the decrease in temperature and/or the increase in strain rate and the softening mechanism primarily proceeded via dynamic recovery.The modification on the conventional Arrhenius-type constitutive model approach was made,the material variables and activation energy were determined to be dependent on the deformation parameters.The modified flow stresses were found to be in close agreement with the experimental values.Furthermore,the activation energy obtained under different deformation conditions showed that it decreased with the rise in temperature and/or strain rate,and was also affected by the coupled effect of strain and strain rate.
文摘The 4340 steel is extensively utilized in several industries including automotive and aerospace for manufac- turing a large number of structural components. Due to the importance of thermo-mechanical processing in the pro- duction of steels, the dynamic recrystallization （DRX） characteristics of 4340 steel were investigated. Namely, hot compression tests on 4340 steel have been performed in a temperature range of 900-- 1200 ℃ and a strain rate range of 0.01--1 s-1 and the strain of up to 0.9. The resulting flow stress curves show the occurrence of dynamic recrys- tallization. The flow stress values decrease with the increase of deformation temperature and the decrease of strain rate. The microstrueture of 4340 steel after deformation has been studied and it is suggested that the evolution of DRX grain structures can be accompanied by considerable migration of grain boundaries. The constitutive equations were developed to model the hot deformation behavior. Finally based on the classical stress-dislocation relations and the kinematics of the dynamic recrystallization; the flow stress constitutive equations for the dynamic recovery period and dynamic reerystallization period were derived for 4340 steel, respectively. The validity of the model was demon- strated by demonstrating the experimental data with the numerical results with reasonable agreement.
基金Financial support from NSFC(Grant No.41572303,4151001059,41101008)Key Projects in the National Science&Technology Pillar Program(2014BAL05B01)CAS"Light of West China"Program
文摘The volume fraction of the solid and liquid phase of debris flows,which evolves simultaneously across terrains,largely determines the dynamic property of debris flows.The entrainment process significantly influences the amplitude of the volume fraction.In this paper,we present a depth-averaged two-phase debris-flow model describing the simultaneous evolution of the phase velocity and depth,the solid and fluid volume fractions and the bed morphological evolution.The model employs the Mohr–Coulomb plasticity for the solid stress,and the fluid stress is modeled as a Newtonian viscous stress.The interfacial momentum transfer includes viscous drag and buoyancy.A new extended entrainment rate formula that satisfies the boundary momentum jump condition(Iverson and Ouyang,2015)is presented.In this formula,the basal traction stress is a function of the solid volume fraction and can take advantage of both the Coulomb and velocity-dependent friction models.A finite volume method using Roe’s Riemann approximation is suggested to solve the equations.Three computational cases are conducted and compared with experiments or previous results.The results show that the current computational model and framework are robust and suitable for capturing the characteristics of debris flows.
基金Supported by the Key Technologies R and D Program of Guangdong Province during the 10~(th) Five-Year Plan Period, No. 2002A3020206
文摘AIM： To establish a highly reproducible animal model of acute liver failure （ALF）, for assessing the effect of bioartificial liver support system （BALSS）. METHODS： A two-phase complete liver devascularization procedure was performed in eight Ioco-hybrid pigs. Blood biochemical index and liver biopsy were studied every 2 h after surgery, and survival time was recorded. The BALSS constructed with high volume recirculating technique was a hollow fiber circulating system consisting of a hepatocyte reactor-hollow fiber module inoculated with microcarrieradhering hepatocytes, and a double pump, heparinized, thermostabilized, micro-capsulized activated carbonadsorbing plasmapheresis system. Twelve pigs undergoing two-phase surgery were randomized into： control group （perfused without hepatocytes, n = 6） and treatment group （perfused with hepatocytes, n = 6）. Intergroup liver biochemical indexes, survival time, and liver pathological changes were analyzed at regular intervals. RESULTS： Two-phase surgery was performed in all the experimental pigs, and there was no obvious difference between their biochemical indexes. After 3 h of phase II surgery, ammonia （Amm） increased to （269＋37）μmol/L. After 5 h of the surgery, fibrinogen （Fib） decreased to （1.5±0.2） g/L. After 7 h of the surgery, ALT, AST, Tbil and PT were （7.6±1.8） nka/L, （40±5） nka/L, （55±8）μmol/L and （17.5±1.7） nka/L respectively. After 9 h of surgery, ALB and Cr were （27±4） g/L and （87±9）μmol/L. After 13 h of surgery, BUN was （3.5±0.9） μmol/L. All the above values were different from those determined before surgery. Survival time of pigs averaged 13.5±1.4 h. ALF pigs in the other group were treated with BALSS. The comparison analysis between the treated and control animals showed the changes of Tbil, PT, AIb, BUN, Cr, Fib, and Amm （P〈0.01）, but there was no change of ALT and AST. The survival time was statistically different （P〈0.01）, and there was no significant difference in histological changes.CONCLUSION： The porcine ALF model established by two-phase devascularized surgery is valid and reproducible. The hollow fiber BALSS can meet the needs of life support and is effective in treating ALF.
基金the National Natural Science Foundation of China (Nos. 42302143, 42172159)China Geological Survey Project (No. DD20211350)support from the G. Albert Shoemaker endowment
文摘Clayey-silt natural gas hydrate reservoirs in the South China Sea exhibit loose and unconsolidated structures, heterogeneous pore structures, high clay mineral contents, and strong hydrophilicity. These characteristics complicate the gas-water two-phase flow process in porous media following hydrate decomposition, posing challenges for efficient development. This study examines the transport response of clayey-silt reservoir samples from the Shenhu area using gas-water two-phase flow experiments and CT scanning to explore changes in pore structure, gas-water distribution, and relative permeability under varying flow conditions. The results indicate that pore heterogeneity significantly influences flow characteristics. Gas preferentially displaces water in larger pores, forming fracture-like pores, which serve as preferential flow channels for gas migration. The preferential flow channels enhance gas-phase permeability up to 19 times that of the water phase when fluid pressures exceed total stresses. However,small pores retain liquid, leading to a high residual water saturation of 0.561. CT imaging reveals that these hydro-fractures improve gas permeability but also confine gas flow to specific channels. Pore network analysis shows that gas injection expands the pore-throat network, enhancing connectivity and forming fracture-like pores. Residual water remains trapped in smaller pores and throats, while structural changes, including new fractures, improve gas flow pathways and overall connectivity. Relative permeability curves demonstrate a narrow gas-water cocurrent-flow zone, a right-shifted iso-permeability point and high reservoir capillary pressure, indicating a strong "water-blocking" effect. The findings suggest that optimizing reservoir stimulation techniques to enhance fracture formation, reduce residual water saturation, and improve gas flow capacity is critical for efficient hydrate reservoir development.
基金supported by the National Natural Science Foundation of China(11722104,11671150)supported by the National Natural Science Foundation of China(11571280,11331005)+3 种基金supported by the National Natural Science Foundation of China(11331005,11771150)by GDUPS(2016)the Fundamental Research Funds for the Central Universities of China(D2172260)FANEDD No.201315
文摘The two-phase flow models are commonly used in industrial applications, such as nuclear, power, chemical-process, oil-and-gas, cryogenics, bio-medical, micro-technology and so on. This is a survey paper on the study of compressible nonconservative two-fluid model, drift-flux model and viscous liquid-gas two-phase flow model. We give the research developments of these three two-phase flow models, respectively. In the last part, we give some open problems about the above models.
基金Supported by the Special Funds for Major State Basic Research Projects, PRC(G1999-0222-08) and the National Natural Science Foundation of China(No. 19872039).
文摘A full second-order moment (FSM) model and an algebraic stress (ASM) two-phase turbulence modelare proposed and applied to predict turbulent bubble-liquid flows in a 2D rectangular bubble column. Predictiongives the bubble and liquid velocities, bubble volume fraction, bubble and liquid Reynolds stresses and bubble-liquidvelocity correlation. For predicted two-phase velocities and bubble volume fraction there is only slight differencebetween these two models, and the simulation results using both two models are in good agreement with the particleimage velocimetry (PIV) measurements. Although the predicted two-phase Reynolds stresses using the FSM are insomewhat better agreement with the PIV measurements than those predicted using the ASM, the Reynolds stressespredicted using both two models are in general agreement with the experiments. Therefore, it is suggested to usethe ASM two-phase turbulence model in engineering application for saving the computation time.
文摘Thermal maturation and petroleum generation modeling of shales is essential for suc- cessful exploration and exploitation of conventional and unconventional oil and gas plays. For basin- wide unconventional resource plays such modeling, when well calibrated with direct maturity meas- urements from wells, can characterize and locate production sweet spots for oil, wet gas and dry gas. The transformation of kerogen to petroleum is associated with many chemical reactions, but models typically focus on first-order reactions with rates determined by the Arrhenius Equation. A miscon- ception has been perpetuated for many years that accurate thermal maturity modeling of vitrinite re- flectance using the Arrhenius Equation and a single activation energy, to derive a time-temperature index （~TTIARa）, as proposed by Wood （1988）, is flawed. This claim was initially made by Sweeney and Burnham （1990） in promoting their ＂EasyRo＂ method, and repeated by others. This paper dem- onstrates through detailed multi-dimensional burial and thermal modeling and direct comparison of the ~TTIARR and ＂EasyRo＂ methods that this is not the case. The ~TTIA^R method not only provides a very useful and sensitive maturity index, it can reproduce the calculated vitrinite reflectance values derived from models based on multiple activation energies （e.g., ＂EasyRo＂）. Through simple expres- sions the ~TTIAaa method can also provide oil and gas transformation factors that can be flexibly scaled and calibrated to match the oil, wet gas and dry gas generation windows. This is achieved in a more-computationally-efficient, flexible and transparent way by the ~TTIARR method than the ＂EasyRo＂ method. Analysis indicates that the ＂EasyRo＂ method, using twenty activation energies and a constant frequency factor, generates reaction rates and transformation factors that do not realisti- cally model observed kerogen behaviour and transformation factors over geologic time scales.
基金financially supported by the Peking University Biomed-X Foundation,China。
文摘The growing demand for brilliant smile and tooth whitening has led to the increasing significance of tooth whitening methods.However,the development of tooth whitening materials with high efficiency and safety has been considered to be an urgent challenge.Here,we report a novel tooth whitening strategy,which overcomes the limitation of conventional methods,shows excellent tooth whitening efficiency and safety,and even exhibits outstanding antibacterial activity.Inspired by stomata and chloroplasts in green leaves,we have developed an integrated two-phase free radical hydrogel(TP-GEL),which integrates solid-phase and liquid-phase free radical functional components fabricated by cold plasma technology.TP-GEL demonstrated safe and ultrafast tooth-whitening effect with or without visible light,which can be more significant than that of 30% H_(2)O_(2),the commonly whitening material in dental clinical practice.More importantly,we also avoid the damage to enamel,such as microhardness,roughness,surface morphology.Benefiting from free radicals,much higher antibacterial properties than commercial products(Chlorhexidine)was obtained.This research provides fundamental design criteria for the development of dual functional oral health care materials with advanced tooth whitening and antibacterial activity.
基金The project supported by the National Natural Science Foundation of China (50176022)
文摘The dense solid-phase governing equations for two-phase flows are obtained by using the kinetic theory of gas molecules.Assuming that the solid-phase velocity distributions obey the Maxwell equations,the collision term for particles under dense two-phase flow conditions is also derived. In comparison with the governing equations of a dilute two-phase flow,the solid-particle's governing equations are developed for a dense turbulent solid-liquid flow by adopting some relevant terms from the dilute two-phase governing equations.Based on Cauchy-Helmholtz theorem and Smagorinsky model, a second-order dynamic sub-grid-scale(SGS)model,in which the sub-grid-scale stress is a function of both the strain-rate tensor and the rotation-rate tensor,is proposed to model the two-phase governing equations by applying dimension analyses.Applying the SIMPLEC algorithm and staggering grid system to the two-phase discretized governing equations and employing the slip boundary conditions on the walls,the velocity and pressure fields,and the volumetric concentration are calculated.The simulation results are in a fairly good agreement with experimental data in two operating cases in a conduit with a rectangular cross-section and these comparisons imply that these models are practical.
基金Supported by the National Natural Science Foundation of China(11171340)
文摘In this work, we obtain the global existence and uniqueness of classical solu-tions to a viscous liquid-gas two-phase model with mass-dependent viscosity and vacuum in one dimension, where the initial vacuum is allowed. We get the upper and lower bounds of gas and liquid masses n and m by the continuity methods which we use to study the compressible Navier-Stokes equations.
