1.

A RayleighPlesset based transport model for cryogenic fluid cavitating flow computations





SHI SuGuo WANG GuoYu HU ChangLi《中国科学:物理学 力学 天文学(英文版)》,2014年第57卷第4期


The present article focuses on modeling issues to simulate cryogenic fluid cavitating flows.A revised cavitation model,in which the thermal effect is considered,is derivated and established based on Kubota model.Cavitating flow computations are conducted around an axisymmetric ogive and a 2D quarter caliber hydrofoil in liquid nitrogen implementing the revised model and Kubota model coupled with energy equation and dynamically updating the fluid physical properties,respecitively.The results show that the revised cavitation model can better describe the mass transport process in the cavitation process in cryogenic fluids.Compared with Kubota model,the revised model can reflect the observed"frosty"appearance within the cavity.The cavity length becomes shorter and it can capture the temperature and pressure depressions more consistently in the cavitating region,particularly at the rear of the cavity.The evaporation rate decreases,and while the magnitude of the condensation rate becomes larger because of the thermal effect terms in the revised model compared with the results obtained by the Kubota model.

2.

Surrogatebased modeling and dimension reduction techniques for multiscale mechanics problems





Wei Shyy YoungChang Cho Amit Gupta ChienChou Tseng Ann Marie Sastry《Acta Mechanica Sinica》,2011年第27卷第6期


Successful modeling and/or design of engineering systems often requires one to address the impact of multiple "design variables" on the prescribed outcome.There are often multiple,competing objectives based on which we assess the outcome of optimization.Since accurate,high fidelity models are typically time consuming and computationally expensive,comprehensive evaluations can be conducted only if an efficient framework is available.Furthermore,informed decisions of the model/hardware’s overall performance rely on an adequate understanding of the global,not local,sensitivity of the individual design variables on the objectives.The surrogatebased approach,which involves approximating the objectives as continuous functions of design variables from limited data,offers a rational framework to reduce the number of important input variables,i.e.,the dimension of a design or modeling space.In this paper,we review the fundamental issues that arise in surrogatebased analysis and optimization,highlighting concepts,methods,techniques,as well as modeling implications for mechanics problems.To aid the discussions of the issues involved,we summarize recent efforts in investigating cryogenic cavitating flows,active flow control based on dielectric barrier discharge concepts,and lithium(Li)ion batteries.It is also stressed that many multiscale mechanics problems can naturally benefit from the surrogate approach for "scale bridging."

3.

Turbulence and cavitation models for timedependent turbulent cavitating flows





ChienChou Tseng《Acta Mechanica Sinica》,2011年第27卷第4期


Cavitation typically occurs when the fluid pressure is lower than the vapor pressure at a local thermodynamic state,and the flow is frequently unsteady and turbulent.To assess the stateoftheart of computational capabilities for unsteady cavitating flows,different cavitation and turbulence model combinations are conducted.The selected cavitation models include several widelyused models including one based on phenomenological argument and the other utilizing interface dynamics.The kε turbulence model with additional implementation of the filter function and density correction function are considered to reduce the eddy viscosity according to the computed turbulence length scale and local fluid density respectively.We have also blended these alternative cavitation and turbulence treatments,to illustrate that the eddy viscosity near the closure region can significantly influence the capture of detached cavity.From the experimental validations regarding the force analysis,frequency,and the cavity visualization,no single model combination performs best in all aspects.Furthermore,the implications of parameters contained in different cavitation models are investigated.The phase change process is more pronounced around the detached cavity,which is better illustrated by the interfacial dynamics model.Our study provides insight to aid further modeling development.

4.

Multiphase fluid dynamics and transport processes of low capillary number cavitating flows 被引次数：1





Wei Shyy《Acta Mechanica Sinica》,2009年第25卷第2期


To better understand the multiphase fluid dynamics and associated transport processes of cavitating flows at the capillary number of 0.74 and 0.54, and to validate the numerical results, a combined computational and experimental investigation of flows around a hydrofoil is studied based on flow visualizations and timeresolved interface movement. The computational model is based on a modified RNG kε model as turbulence closure, along with a vaporliquid mass transfer model for treating the cavitation process. Overall, favorable agreement between the numerical and experimental results is observed. It is shown that the cavi tation structure depends on the interaction of the watervapor mixture and the vapor among the whole cavitation stage, the interface between the vapor and the twophase mixture exhibits substantial unsteadiness. And, the adverse motion of the interface relates to pressure and velocity fluctuations inside the cavity. In particular, the velocity in the vapor region is lower than that in the twophase region.

5.

ELASTICPLASTIC DYNAMIC RESPONSE OF FULLY BACKED SANDWICH PLATES UNDER LOCALIZED IMPULSIVE LOADING 被引次数：1





Hua Liu Wuchao Chen Jialing Yang《Acta Mechanica Solida Sinica》,2010年第23卷第4期


An analytical model is developed to assess the elasticplastic dynamic response of fully backed sandwich plates under localized impulse load.The core is modeled as an elasticperfectly plastic foundation.The top face sheet is treated as an individual plate resting on the foundation.The elasticplastic analysis for the top face sheet is based on a minimum principle in dynamic plasticity associated with the finite difference technique.The effects of spatial and temporal distributions of the impulsive loading on the dynamic response of sandwich plates are discussed.The model can be used to predict the impulseinduced local effect on fully backed sandwich plates.

6.

3D numerical simulation on fluidstructure interaction of structure subjected to underwater explosion with cavitation





张阿漫 任少飞 李青 李佳《应用数学和力学(英文版)》,2012年第33卷第9期


In the underwatershock environment,cavitation occurs near the structural surface.The dynamic response of fluidstructure interactions is influenced seriously by the cavitation effects.It is also the difficulty in the field of underwater explosion.With the traditional boundary element method and the finite element method(FEM),it is difficult to solve the nonlinear problem with cavitation effects subjected to the underwater explosion.To solve this problem,under the consideration of the cavitation effects and fluid compressibility,with fluid viscidity being neglected,a 3D numerical model of transient nonlinear fluidstructure interaction subjected to the underwater explosion is built.The fluid spectral element method(SEM) and the FEM are adopted to solve this model.After comparison with the FEM,it is shown that the SEM is more precise than the FEM,and the SEM results are in good coincidence with benchmark results and experiment results.Based on this,combined with ABAQUS,the transient fluidstructure interaction mechanism of the 3D submerged spherical shell and ship stiffened plates subjected to the underwater explosion is discussed,and the cavitation region and its influence on the structural dynamic responses are presented.The paper aims at providing references for relevant research on transient fluidstructure interaction of ship structures subjected to the underwater explosion.

7.

A Thermodynamic Cavitation Model for Cavitating Flow Simulation in a Wide Range of Water Temperatures





张瑶 罗先武 季斌 刘树红 吴玉林 许洪元、《中国物理快报》,2010年第1期


A thermodynamic cavitation model is developed to simulate the cavitating water flow in a wide temperature range. The thermal effect on bubble growth during cavitation is introduced in the developed model by considering both pressure difference and heat transfer between the vapor and liquid phase. The cavitating turbulent flow over a NACA0015 hydrofoil has been simulated at various temperatures from room temperature to 150°C by using the present cavitation model, which has been validated by the experimental data. It is seen that the thermodynamic effects of cavitation, vapor depression and temperature depression are much more predominant in high temperature water compared with those in room temperature water. These results indicate that the proposed thermodynamic cavitation model is reasonably applicable to the cavitating water flow in a wide temperature range.

8.

Semianalytical and computational investigation of different dust loading structures affecting the performance of a fibrous air filter





Bin Xu ;Ya Wu ;Pengyi Cui《Particuology》,2014年第2期


In this study, a semianalytical model was developed to illustrate the relationship between filtration performance （filtration efficiency and pressure drop） and dust loading under two different particle deposit structures based on theoretical analysis and computational fluid dynamic （CFD） technology. Under the compact deposit structure, within the practical parameter ranges （fiber diameter, air velocity, dust loading mass）, a slight efficiency enhancement （∽10%） occurred at the most penetration particle size （MPPS） and pressure drop increased significantly （∽100%） in response to the solidity increase from 5% to 15%. However, under the dendritic particle deposit structure, both filtration efficiency （∽40%） and pressure drop （4600%） increased significantly with the same solidity increase due to the larger air velocity and swerve change between fibers.

9.

Characteristics of Electrorheological Fluid Flow in Journal Bearings





张准 朱克勤《中国物理快报》,2002年第19卷第2期


Under the influence of an applied electric field,the variation of apparent viscosity of electrorheological(ER) fluid flow causes ER effects.According to the Bingham model,which is widely used for describing the rheological properties of ER fluids,this variation should be very weak at high shear rates.To chlarify the ER effects in ER journal bearings at high shear rate,a numerical study is presented.It is found that under the influence of the applied electric field,ER effects in ER journal bearings can be affected by not only the apparent viscosity of ER fluids but also the movement of yield surface in the clearance of ER journal bearing.In the case of low shear rate,both are effective on the lubricant film pressure of ER journal bearings.In the case of high shear rates,the main factor is the extension of nonyield region in the bearing clearance.

10.

Cavitation Simulation with Consideration of the Viscous Effect at Large Liquid Temperature Variation





于安 ;罗先武 ;季斌 ;黄仁芳 ;HIDALGOVictor ;KIMSongHak《中国物理快报》,2014年第8期


The phase change due to cavitation is not only driven by the pressure difference between the local pressure and vapor saturated pressure, but also affected by the physical property changes in the case of large liquid temperature variation. The present work simulates cavitation with consideration of the viscous effect as well as the local variation of vapor saturated pressure, density, etc. A new cavitation model is developed based on the bubble dynamics, and is applied to analyze the eavitating flow around an NACA0015 hydrofoil at different liquid temperatures from 25℃ to 150℃. The results by the proposed model, such as the pressure distribution along the hydrofoil wall surface, vapor volume fraction, and source term of the mass transfer rate due to cavitation, are compared with the available experimental data and the numerical results by an existing thermodynamic model. It is noted that the numerical results by the proposed cavitation model have a slight discrepancy from the experimental results at room temperature, and the accuracy is better than the existing thermodynamic cavitation model. Thus the proposed cavitation model is acceptable for the simulation of cavitating flows at different liquid temperatures.

11.

Modeling of fluid dynamics interacting with ductile fraction propagation in high pressure pipeline





Mihaela Popescu《Acta Mechanica Sinica》,2009年第25卷第3期


This paper presents a computational model for the fluid dynamics in a fractured ductile pipe under high pressure. The pressure profile in front of the crack tip, which is the driving source of crack propagation, is computed using a nonlinear wave equation. The solution is coupled with a one dimensional choked flow analysis behind the crack. The simulation utilizes a high order optimized prefactored compactfinite volume method in space, and low dispersion and dissipation RungeKutta in time. As the pipe fractures the rapid depressurization take place inside the pipe and the propagation of the crackinduced waves strongly influences the outflow dynamics. Consistent with the experimental observation, the model predicts the expansion wave inside the pipe, and the reflection and outflow of the wave. The model also helps characterize the propagation of the crack dynamics and fluid flows around the tip of the crack.

12.

Flow structures of gaseous jets injected into water for underwater propulsion 被引次数：4





Wei Shyy《Acta Mechanica Sinica》,2011年第27卷第4期


Gaseous jets injected into water are typically found in underwater propulsion,and the flow is essentially unsteady and turbulent.Additionally,the high watertogas density ratio can result in complicated flow structures;hence measuring the flow structures numerically and experimentally remains a challenge.To investigate the performance of the underwater propulsion,this paper uses detailed NavierStokes flow computations to elucidate the gaswater interactions under the framework of the volume of fluid(VOF) model.Furthermore,these computations take the fluid compressibility,viscosity,and energy transfer into consideration.This paper compares the numerical results and experimental data,showing that phenomena including expansion,bulge,necking/breaking,and backattack are highlighted in the jet process.The resulting analysis indicates that the pressure difference on the rear and front surfaces of the propulsion system can generate an additional thrust.The strong and oscillatory thrust of the underwater propulsion system is caused by the intermittent pulses of the back pressure and the nozzle exit pressure.As a result,the total thrust in underwater propulsion is not only determined by the nozzle geometry but also by the flow structures and associated pressure distributions.

13.

Poroelastic behaviors of the osteon: A comparison of two theoretical osteon models





XiaoGang Wu WeiYi Chen《Acta Mechanica Sinica》,2013年第29卷第4期


In the paper, two theoretical poroelastic osteon models are presented to compare their poroelastic behaviors, one is the hollow osteon model (Haversian fluid is neglected) and the other is the osteon model with Haversian fluid considered. They both have the same two types of impermeable exterior boundary conditions, one is elastic restraint and the other is displacement constrained, which can be used for analyzing other experiments performed on similarly shaped poroelastic specimens. The obtained analytical pressure and velocity solutions demonstrate the effects of the loading factors and the material parameters, which may have a significant stimulus to the mechanotransduction of bone remodeling signals. Model comparisons indicate: (1) The Haversian fluid can enhance the whole osteonal fluid pressure and velocity fields. (2) In the hollow model, the key loading factor governing the poroelastic behavior of the osteon is strain rate, while in the model with Haversian fluid considered, the strain rate governs only the velocity. (3) The pressure amplitude is proportional to the loading frequency in the hollow model, while in the model with Haversian fluid considered, the loading frequency has little effect on the pressure amplitude.

14.

Dynamical calculation and analysis on penetration of target plates by truncated conical projectiles





Gao Shiqiao and Wang Baoxing《应用数学和力学(英文版)》,1986年第7卷第11期


In this paper, dynamical calculation and analysis are made on penetration of thin plates by truncated conical projectiles in terms of the needs of fuze designing. The impact velocity ranges from 200w/s ts to 1000m/s (including both low and high velocities). The target plates include the thin aluminium plate (metal) and the plywood (nonmetal).Because a strength effect of target plates is considered in the establishment of dynamical models, we solved the problem that some previous models were not suitable to lowvelocity impact, for example, M. Zaid and B. Paul’s models [1][2][3] Bv comparison of menial effect with strength effect, we theoretically proved Zaid and Paul’s experimental conclusion131: "Only when the impact velocity is more that 500m/s can the strength effect be neglected. Otherwise this effect can not be neglected".

15.

Investigation on Rijke pipe＇s acoustic characteristics by numerical simulation： modeling the pulsing flow field coupled the inner of pipe with its outer space





ZHONG Yingjie DENG Kai ZHANG Guojun LIN Haihao LI Hua《Chinese Journal of Acoustics》,2008年第27卷第3期


Based on the results of fluid dynamics, heat transfer and acoustics, a Computational Fluid Dynamics （CFD） method was utilized to study the acoustic characteristics and selfexcited pulsation mechanism inside a Rijke pipe. To avoid settling the irrational boundary conditions of the finiteamplitude standing wave in the Rijke thermoacoustic system, the simulation modeling in the flow field, which coupled the inner of pipe with its outer space, was carried out to replace the traditional way in form of internal flow field numerical investigations. A hypothesis for heat source in energy equation including the relationship on unsteady heat of air around heat source, oscillation pressure and oscillation velocity was presented. To reflect the essence of Rijke pipe, simulation on selfexcited oscillation was conducted by means of its own pulsation of pressure, velocity and temperature. This method can make the convergence process steady and effectively avoid divergence. The physical phenomenon of the selfexcited Rijke pipe was analyzed. Moreover, the mechanisms on the Rijke pipe＇s selfexcited oscillation were explained. Based on this method, comparative researches on the acoustic characteristic of the Rijke pipe with different size and different shape of nozzle were performed. The simulation results agreed with the experimental data satisfactorily. The results show that this numerical simulation can be used to study the sound pressure of nozzle for the engineering application of Rijke pipes.

16.

COMPUTATIONAL FLUID DYNAMICS FOR DENSE GASSOLID FLUIDIZED BEDS： A MULTISCALE MODELING STRATEGY





M.A.vanderHoef M.vanSintAnnaland J.A.M.Kuipers《中国颗粒学报》,2005年第3卷第1期


Dense gasparticle flows are encountered in a variety of industrially important processes for large scale production of fuels, fertilizers and base chemicals. The scaleup of these processes is often problematic and is related to the intrinsic complexities of these flows which are unfortunately not yet fully understood despite significant efforts made in both academic and industrial research laboratories. In dense gasparticle flows both (effective) fluidparticle and (dissipative) particleparticle interactions need to be accounted for because these phenomena to a large extent govern the prevailing flow phenomena, i.e. the formation and evolution of heterogeneous structures. These structures have significant impact on the quality of the gassolid contact and as a direct consequence thereof strongly affect the performance of the process. Due to the inherent complexity of dense gasparticles flows, we have adopted a multiscale modeling approach in which both fluidparticle and particleparticle interactions can be properly accounted for. The idea is essentially that fundamental models, taking into account the relevant details of fluidparticle (lattice Boltzmann model) and particleparticle (discrete particle model) interactions, are used to develop closure laws to feed continuum models which can be used to compute the flow structures on a much larger (industrial) scale. Our multiscale approach (see Fig. 1 ) involves the lattice Boltzmann model, the discrete particle model, the continuum model based on the kinetic theory of granular flow and the discrete bubble model. In this paper we give an overview of the multiscale modeling strategy, accompanied by illustrative computational results for bubble formation. In addition, areas which need substantial further attention will be highlighted.

17.

Dynamical evolution processes of traffic flow and travel cost in urban transportation networks





郭仁拥 黄海军《中国物理 B》,2008年第17卷第5期


Considering such a fact that travellers dynamically adjust their routes and the resultant link traffic flows in a network evolve over time, this paper proposes a dynamical evolutionary model of the traffic assignment problem with endogenous origindestination （OD） demands. The model＇s stability is analysed and the resultant user equilibrium （UE） state is shown to be stable under certain conditions. Numerical results in a grid network indicate that the model can generate convergent flow patterns and finally terminates at the UE state. Impacts by the parameters associated with OD demand function and link cost function are also investigated.

18.

ON THE COUPLING METHODS FOR COUPLED PROBLEMS





冯振兴 T.C.Huang《数学物理学报(B辑英文版)》,1987年第2期


The coupled problem means fluidstructure interaction widely encountered in aviation, offshore and nuclear engineerings. The coupling method here means the combination of finite and boundary elements(FE/BE)to improve the computational effciency considerably. In this paper, a general math. Model for simulation of the wetted structure dynamic response to inter/external fluid flow is presented. In particular, the various boundary conditions for fluid region are treated sophsticatodiy. In this way, only the displacement and pressure remain to be the independent variables so that both computer cost and accuracy could be improved. The FORTRAN program package of this model has been compiled on #Univac1110 in Madison (MACC), USA, and on #M340S computer in Wuhan University, China. As a first approximation, in this paper a 2D example for the shipwave interaction analysis is illustrated.

19.

3D numerical simulation on fluidstructure interaction of structure subjected to underwater explosion with cavitation





Aman ZHANG Shaofei REN Qing LI Jia LI《应用数学和力学》,2012年第33卷第9期


In the underwatershock environment,cavitation occurs near the structural surface.The dynamic response of fluidstructure interactions is influenced seriously by the cavitation effects.It is also the d...

20.

Kinetic modeling of a high power fastaxialflow CO_2 laser with computational fluid dynamics method





《中国光学快报(英文版)》,2008年第7期


A new computational fluid dynamics (CFD) method for the simulation of fastaxialflow CO_2 laser is developed.The model which is solved by CFD software uses a set of dynamic differential equations to describe the dynamic process in one discharge tube.The velocity,temperature,pressure and turbulence energy distributions in discharge passage are presented.There is a good agreement between the theoret ical prediction and the experimental results.This result indicates that the parameters of the laser have significant effect on the flow distribution in the discharge passage.It is helpful to optimize the output of high power CO_2 laser by mastering its kinetic characteristics.
