Entity

Time filter

Source Type


Xiang Q.,National Laboratory for Computational Fluid Dynamics | Wu S.,National Laboratory for Computational Fluid Dynamics
Lecture Notes in Electrical Engineering | Year: 2012

Lots of problems focus on large positive definite linear systems in science and engineering. It is crucial to solve the systems stably and efficiently. There are two categories of iterative methodologies. One is based on the splitting of coefficient matrices, such as the Jacobi, Gauss-Seidel and successive over relaxation (SOR) iterations. © 2012 Springer-Verlag London Limited. Source


Kwang-Hua C.R.,BeiHang Training Center | Kwang-Hua C.R.,Distribution Center | Li Z.,China Aerodynamics Research And Development Center | Li Z.,National Laboratory for Computational Fluid Dynamics
Fluid Phase Equilibria | Year: 2015

Transport of the solid helium with imbedded defects in confined domains has been recently reported. Here we used the verified absolute-reaction theory which originates from the quantum chemistry approach together with the boundary perturbation approach to calculate the temperature-dependent viscosity of flowing solid He-4 in the bulk. Both effects of the activation energy and activation volume on the temperature-dependent (shear) viscosity of flowing solid He-4 were illustrated. We found that the temperature-dependent (shear) viscosity which is a ratio of the shear stress and the shear strain rate increases a little as the temperature decreases within the selected temperature regime. © 2015 Elsevier B.V. Source


Yang J.-Y.,National Taiwan University | Muljadi B.P.,Fondation de Cooperation Scientifique | Muljadi B.P.,University Paul Sabatier | Chen S.-Y.,National Taiwan University | And 2 more authors.
Computers and Fluids | Year: 2013

The developments of several kinetic numerical methods for solving the semiclassical Boltzmann-BGK equation are presented. The methods considered include the direct solver in phase space and lattice Boltzmann method. For the direct phase space solver, the discrete ordinate methods in velocity space and explicit and implicit high resolution schemes in physical space are combined to yield the desired scheme. A brief overview of the core computational methods which has been originated and evolved over the past 30. years starting at NASA-Ames/Stanford is reviewed. For the semiclassical lattice Boltzmann method, a multiple relaxation time approach is developed. The method is directly derived by projecting the kinetic governing equation onto the tensor Hermite polynomials and various hydrodynamic approximation orders can be achieved. The semiclassical incompressible Navier-Stokes equations can be recovered via a Chapman-Enskog multi-scale expansion. Applications of these kinetic numerical methods to semiclassical hydrodynamic transport involving various kinds of carrier particles are then illustrated by specific examples. The general hydrodynamic transports in gases of arbitrary statistics and in wide flow regimes are emphasized. The results indicate distinct characteristics of the effects of quantum statistics. © 2013 Elsevier Ltd. Source


Li Z.-H.,China Aerodynamics Research And Development Center | Li Z.-H.,National Laboratory for Computational Fluid Dynamics | Ma Q.,China Aerodynamics Research And Development Center | Ma Q.,National Laboratory for Computational Fluid Dynamics | Cui J.,CAS Academy of Mathematics and Systems Science
Journal of Computational Physics | Year: 2016

The new second-order two-scale (SOTS) finite element algorithm is developed for the dynamic thermo-mechanical coupling problems in axisymmetric and spherical symmetric structures made of composite materials. The axisymmetric structure considered is periodic in both radial and axial directions and homogeneous in circumferential direction. The spherical symmetric structure is only periodic in radial direction. The dynamic thermo-mechanical coupling model is presented and the equivalent compact form is derived. Then, the cell problems, effective material coefficients and the homogenized thermo-mechanical coupling problem are obtained successively by the second-order asymptotic expansion of the temperature increment and displacement. The homogenized material obtained is manifested with the anisotropic property in the circumferential direction. The explicit expressions of the homogenized coefficients in the plane axisymmetric and spherical symmetric cases are given and both the derivation of the analytical solutions of the cell functions and the quasi-static thermoelasticity problems are discussed. Based on the SOTS method, the corresponding finite-element procedure is presented and the unconditionally stable implicit algorithm is established. Some numerical examples are solved and the mutual interaction between the temperature and displacement field is studied under the condition of structural vibration. The computational results demonstrate that the second-order asymptotic analysis finite-element algorithm is feasible and effective in simulating and predicting the dynamic thermo-mechanical behaviors of the composite materials with small periodic configurations in axisymmetric and spherical symmetric structures. This may provide a vital computational tool for analyzing composite material internal temperature distribution and structural deformation induced by the dynamic thermo-mechanical coupling response under strong aerothermodynamic environment. © 2016 The Authors. Source


Ma Q.,China Aerodynamics Research And Development Center | Ma Q.,National Laboratory for Computational Fluid Dynamics | Cui J.,CAS Academy of Mathematics and Systems Science | Li Z.,China Aerodynamics Research And Development Center | Li Z.,National Laboratory for Computational Fluid Dynamics
International Journal of Solids and Structures | Year: 2016

A new second-order two-scale (SOTS) analysis finite element algorithm is developed for the axisymmetric and spherical symmetric elastic problems with small periodic configurations. The axisymmetric structure considered is periodic in both radial and axial directions and homogeneous in circumferential direction, and the spherical symmetric structure is only periodic in radial direction and homogeneous in other two directions. The SOTS asymptotic expansions for the space problem, plane axisymmetric problem, and spherical symmetric problem are presented, and the main feature is that the anisotropic material is obtained by the homogenization. The analytical expressions of the cell functions and homogenized solutions for plane axisymmetric and spherical symmetric problems are obtained, and the error estimations of the expansions are established. The second-order asymptotic analysis finite-element algorithm is presented and the numerical examples are solved including the hollow cylinder, rotating disk and hollow sphere composed of periodic composite materials. The computational results demonstrate the effectiveness and accuracy of the SOTS asymptotic analysis algorithm, and the converging behavior of the asymptotic analysis algorithm agrees well with the theoretical prediction. It is also indicated that the stress distributions can be correctly computed only by adding the second-order correctors. © 2015 Elsevier Ltd. Source

Discover hidden collaborations