The present paper reviews the recent developments of a high⁃order⁃spectral method(HOS)and the combination with computational fluid dynamics(CFD)method for wave⁃structure interactions.As the numerical simulations of wa...The present paper reviews the recent developments of a high⁃order⁃spectral method(HOS)and the combination with computational fluid dynamics(CFD)method for wave⁃structure interactions.As the numerical simulations of wave⁃structure interaction require efficiency and accuracy,as well as the ability in calculating in open sea states,the HOS method has its strength in both generating extreme waves in open seas and fast convergence in simulations,while computational fluid dynamics(CFD)method has its advantages in simulating violent wave⁃structure interactions.This paper provides the new thoughts for fast and accurate simulations,as well as the future work on innovations in fine fluid field of numerical simulations.展开更多
The flexible transmission shaft and wheel propeller are combined as the kinetic source equipment,which realizes the multi-motion modes of the autonomous underwater vehicle(AUV) such as vectored thruster and wheeled mo...The flexible transmission shaft and wheel propeller are combined as the kinetic source equipment,which realizes the multi-motion modes of the autonomous underwater vehicle(AUV) such as vectored thruster and wheeled movement.In order to study the interactional principle between the hull and the wheel propellers while the AUV navigating in water,the computational fluid dynamics(CFD) method is used to simulate numerically the unsteady viscous flow around AUV with propellers by using the Reynolds-averaged Navier-Stokes(RANS) equations,shear-stress transport(SST) k-w model and pressure with splitting of operators(PISO) algorithm based on sliding mesh.The hydrodynamic parameters of AUV with propellers such as resistance,pressure and velocity are got,which reflect well the real ambient flow field of AUV with propellers.Then,the semi-implicit method for pressure-linked equations(SIMPLE) algorithm is used to compute the steady viscous flow field of AUV hull and propellers,respectively.The computational results agree well with the experimental data,which shows that the numerical method has good accuracy in the prediction of hydrodynamic performance.The interaction between AUV hull and wheel propellers is predicted qualitatively and quantitatively by comparing the hydrodynamic parameters such as resistance,pressure and velocity with those from integral computation and partial computation of the viscous flow around AUV with propellers,which provides an effective reference to the study on noise and vibration of AUV hull and propellers in real environment.It also provides technical support for the design of new AUVs.展开更多
Gao＇s viscous/in-viscid interacting shear flows （ISF） theory, proposed by professor Gao Zhi in Institute of Mechanics, China Academy of Science, and its inferences and their applications in computational fluid dyna...Gao＇s viscous/in-viscid interacting shear flows （ISF） theory, proposed by professor Gao Zhi in Institute of Mechanics, China Academy of Science, and its inferences and their applications in computational fluid dynamics （CFD） are reviewed and some subjects worthy to be studied are pro- posed in this paper. The flow-field and motion law of ISF, mathematics definition of strong viscous shear layer flow in ISF, ISF equations, wall-surface compatibility criteria （Gao＇s criteria ）, space scale variety law of strong viscous shear layer reveals flow mechanism and local space small scale triggered by strong interaction that cause some abnormal severe local pneumatic heating phenomenon in hypersonic flow. Gao＇s ISF theory was used in near wall flow, free ISF flow simulation and design of computing grids, Gao＇s wall-surface criteria were used to verify calculation reliability and accuracy of near wall flows, ISF theory approximate analytical result of shock waves-boundary layer interac- tion and ISF equations were used to obtain the numerical exact solution of local area flow （ such as stationary point flow）. Some new subjects, such as, improving near-wall turbulent models according to the turbulent flow simulation satisfying the wall-criteria and illustrating relation between grid-con- vergence based on the wall criteria and other convergence tactics, are suggested. The necessity of applying Gao＇s ISF theory and wall criteria is revealed. Difficulties and importance of hypersonic vis- cous/in-viscid interaction phenomenon were also emphasized.展开更多
Supersonic viscous flows past blunt bodies is calculated with TVD difference scheme and implicit Lower Upper Symmetric Gauss Seidel (LU SGS) method, and parallel programming designing software platform PVM is used b...Supersonic viscous flows past blunt bodies is calculated with TVD difference scheme and implicit Lower Upper Symmetric Gauss Seidel (LU SGS) method, and parallel programming designing software platform PVM is used based on message passing to distribute a large task according to some patching strategies to a large number of processors in the network. These processors accomplish this large task together. The marked improvement of computational efficiency in networks, especially in MPP system, demonstrates the potential vitality of CFD in engineering design.展开更多
In this paper,the author recounts his forty-year plus struggle to find a sound basis for understanding the computational fluid dynamics of compressible flow.
基金National Natural Science Foundation of China(Grant No.51879159)the National Key Research and Development Program of China(Grant Nos.2019YFB1704200 and 2019YFC0312400)+2 种基金the Chang Jiang Scholars Program(Grant No.T2014099)the Shanghai Excellent Academic Leaders Program(Grant No.17XD1402300)the Innovative Special Project of Numerical Tank of Ministry of Industry and Information Technology of China(Grant No.2016-23/09).
文摘The present paper reviews the recent developments of a high⁃order⁃spectral method(HOS)and the combination with computational fluid dynamics(CFD)method for wave⁃structure interactions.As the numerical simulations of wave⁃structure interaction require efficiency and accuracy,as well as the ability in calculating in open sea states,the HOS method has its strength in both generating extreme waves in open seas and fast convergence in simulations,while computational fluid dynamics(CFD)method has its advantages in simulating violent wave⁃structure interactions.This paper provides the new thoughts for fast and accurate simulations,as well as the future work on innovations in fine fluid field of numerical simulations.
基金Project(2006AA09Z235) supported by National High Technology Research and Development Program of ChinaProject(CX2009B003) supported by Hunan Provincial Innovation Foundation For Postgraduate,China
文摘The flexible transmission shaft and wheel propeller are combined as the kinetic source equipment,which realizes the multi-motion modes of the autonomous underwater vehicle(AUV) such as vectored thruster and wheeled movement.In order to study the interactional principle between the hull and the wheel propellers while the AUV navigating in water,the computational fluid dynamics(CFD) method is used to simulate numerically the unsteady viscous flow around AUV with propellers by using the Reynolds-averaged Navier-Stokes(RANS) equations,shear-stress transport(SST) k-w model and pressure with splitting of operators(PISO) algorithm based on sliding mesh.The hydrodynamic parameters of AUV with propellers such as resistance,pressure and velocity are got,which reflect well the real ambient flow field of AUV with propellers.Then,the semi-implicit method for pressure-linked equations(SIMPLE) algorithm is used to compute the steady viscous flow field of AUV hull and propellers,respectively.The computational results agree well with the experimental data,which shows that the numerical method has good accuracy in the prediction of hydrodynamic performance.The interaction between AUV hull and wheel propellers is predicted qualitatively and quantitatively by comparing the hydrodynamic parameters such as resistance,pressure and velocity with those from integral computation and partial computation of the viscous flow around AUV with propellers,which provides an effective reference to the study on noise and vibration of AUV hull and propellers in real environment.It also provides technical support for the design of new AUVs.
基金Supported by the National Natural Science Foundation(10702009)
文摘Gao＇s viscous/in-viscid interacting shear flows （ISF） theory, proposed by professor Gao Zhi in Institute of Mechanics, China Academy of Science, and its inferences and their applications in computational fluid dynamics （CFD） are reviewed and some subjects worthy to be studied are pro- posed in this paper. The flow-field and motion law of ISF, mathematics definition of strong viscous shear layer flow in ISF, ISF equations, wall-surface compatibility criteria （Gao＇s criteria ）, space scale variety law of strong viscous shear layer reveals flow mechanism and local space small scale triggered by strong interaction that cause some abnormal severe local pneumatic heating phenomenon in hypersonic flow. Gao＇s ISF theory was used in near wall flow, free ISF flow simulation and design of computing grids, Gao＇s wall-surface criteria were used to verify calculation reliability and accuracy of near wall flows, ISF theory approximate analytical result of shock waves-boundary layer interac- tion and ISF equations were used to obtain the numerical exact solution of local area flow （ such as stationary point flow）. Some new subjects, such as, improving near-wall turbulent models according to the turbulent flow simulation satisfying the wall-criteria and illustrating relation between grid-con- vergence based on the wall criteria and other convergence tactics, are suggested. The necessity of applying Gao＇s ISF theory and wall criteria is revealed. Difficulties and importance of hypersonic vis- cous/in-viscid interaction phenomenon were also emphasized.
文摘Supersonic viscous flows past blunt bodies is calculated with TVD difference scheme and implicit Lower Upper Symmetric Gauss Seidel (LU SGS) method, and parallel programming designing software platform PVM is used based on message passing to distribute a large task according to some patching strategies to a large number of processors in the network. These processors accomplish this large task together. The marked improvement of computational efficiency in networks, especially in MPP system, demonstrates the potential vitality of CFD in engineering design.
文摘In this paper,the author recounts his forty-year plus struggle to find a sound basis for understanding the computational fluid dynamics of compressible flow.
