Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Stokes equations”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Turbulence modeling based on direct simulation of the Navier-Stokes equations

The underlying physics of the transport equation for turbulence dissipation is analyzed. The study is developed based on the dimensional analysis of turbulence scales, higher-order rapid distortion assumptions, and direct numerical simulations. A preliminary turbulence model for the dissipation rate of turbulent kinetic energy is proposed; allowance is made for the effects of mean rotation rates on the production and removal of dissipation rate. It is shown that the production of dissipation due to mean-velocity gradients is proportional to the production of turbulent kinetic energy.

Bardina, Jorge↗
NASA NTRS1987

Development of generalized block correction procedures for the solution of discretized Navier-Stokes equations

Effort is directed towards developing a solution method which combines advantages of both the iterative and the direct methods. It involves iterative solution on the fine grid, convergence of which is enhanced by a direct solution for correction quantities on a coarse grid. The proposed block correction procedure was applied to compute recirculating flow in a driven cavity.

Kelkar, Kanchan M.↗
NASA NTRS1989

Application of direct solvers to unstructured meshes for the Euler and Navier-Stokes equations using upwind schemes

The application of Newton iteration to inviscid and viscous airfoil calculations on unstructured meshes is examined. A cell-centered finite volume scheme is employed on an unstructured mesh consisting of triangles. Roe's flux difference splitting scheme is used to compute the inviscid fluxes. Higher order accuracy is achieved by an interpolation procedure that makes use of auxiliary gradients. The efficient solution of the sparse linear system of equations which arises upon linearization in time is addressed. Results are presented for inviscid and viscous test cases. The complications which arise due to the introduction of nonlinear limiters are addressed.

Venkatakrishnan, V.↗
NASA NTRS1989

Solution of the incompressible Navier-Stokes equations using artificial compressibility methods

A modified artificial compressibility formulation is derived from a preconditioned low Mach number compressible formulation, and these two methods are compared on a two-dimensional laminar leading edge flow using a LBI/ADI solution algorithm. The two methods are essentially equivalent with appropriate preconditioning parameters and have the same convergence rates and efficiency, giving 4 orders of residual reduction in about 75 iterations with a vectorized CRAY-XMP run time of 20 seconds for 3000 grid points.

Briley, W. R.↗
NASA NTRS1989

Computation of Navier-Stokes equations for three-dimensional flow separation

Supersonic flows over a sharp and a flat-faced blunt fin mounted on a flat plate are simulated numerically. Several basic issues involved in the resultant three-dimensional steady flow separation are studied. Using the same number of grid points, different grid spacings are employed to investigate the effects of a grid resolution on the origin of the line of separation. Various shock strengths are used to study the so-called separated and unseparated boundary layer and to establish the existence or absence of secondary separation. The length of separation ahead of the flat-faced blunt fin, bifurcation of a horseshoe vortex, and the accessibility of a closed-type separation are investigated. The usual interpretation of the flow field from previous studies and new interpretations arising from the present simulation are discussed.

Hung, Ching-Mao↗
NASA NTRS1989

Numerical solutions of the complete Navier-Stokes equations

A hybrid Reynolds averaged/assumed probability density function (PDF) approach was developed and applied to the study of turbulent combustion in a supersonic mixing layer. This approach was used to address the laminar-like treatment of the thermochemical terms that appear in the conservation equations. Calculations were carried out for two experiments involving H2-air supersonic turbulent mixing. A SPARK combustion model was employed. In general, the approach shows modest improvement over previous calculations.

Hassan, H. A.↗
NASA NTRS1990

A comparison of two central difference schemes for solving the Navier-Stokes equations

Five viscous transonic airfoil cases were computed by two significantly different computational fluid dynamics codes: An explicit finite-volume algorithm with multigrid, and an implicit finite-difference approximate-factorization method with Eigenvector diagonalization. Both methods are described in detail, and their performance on the test cases is compared. The codes utilized the same grids, turbulence model, and computer to provide the truest test of the algorithms. The two approaches produce very similar results, which, for attached flows, also agree well with experimental results; however, the explicit code is considerably faster.

Maksymiuk, C. M.↗
NASA NTRS1988

Thrust Chamber Modeling Using Navier-Stokes Equations: Code Documentation and Listings

A copy of the PHOENICS input files and FORTRAN code developed for the modeling of thrust chambers is given. These copies are contained in the Appendices. The listings are contained in Appendices A through E. Appendix A describes the input statements relevant to thrust chamber modeling as well as the FORTRAN code developed for the Satellite program. Appendix B describes the FORTRAN code developed for the Ground program. Appendices C through E contain copies of the Q1 (input) file, the Satellite program, and the Ground program respectively.

Daley, P. L.↗
NASA NTRS1990

Flow computations for the Space Shuttle in ascent mode using thin-layer Navier-Stokes equations

The application of CFD techniques to the Space Shuttle ascent environment was aggressively undertaken in the wake of the Challenger accident in order to secure a major new source of aerodynamic information for both the nominal and mission-abort conditions, using Cray 2 and Cray YMP supercomputers. Due to the integrated vehicle's complexity, the 'chimera' composite grid approach, in which an overset body-conforming grid is used to represent each geometric component as well as special flow regions, was employed for the discretization process. Calculation results exhibit general agreement in both flow structure and surface pressure with the available wind tunnel and flight-test results.

Martin, F. W., Jr.↗