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Effects of artificial viscosity on the accuracy of high-reynolds-number kappa-epsilon turbulence model
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Chitsomboon, Tawit |
| Copyright Year | 1994 |
| Description | Wall functions, as used in the typical high Reynolds number k-epsilon turbulence model, can be implemented in various ways. A least disruptive method (to the flow solver) is to directly solve for the flow variables at the grid point next to the wall while prescribing the values of k and epsilon. For the centrally-differenced finite-difference scheme employing artificial viscocity (AV) as a stabilizing mechanism, this methodology proved to be totally useless. This is because the AV gives rise to a large error at the wall due to too steep a velocity gradient resulting from the use of a coarse grid as required by the wall function methodology. This error can be eliminated simply by extrapolating velocities at the wall, instead of using the physical values of the no-slip velocities (i.e. the zero value). The applicability of the technique used in this paper is demonstrated by solving a flow over a flat plate and comparing the results with those of experiments. It was also observed that AV gives rise to a velocity overshoot (about 1 percent) near the edge of the boundary layer. This small velocity error, however, can yield as much as 10 percent error in the momentum thickness. A method which integrates the boundary layer up to only the edge of the boundary (instead of infinity) was proposed and demonstrated to give better results than the standard method. |
| File Size | 822493 |
| Page Count | 24 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19950011241 |
| Archival Resource Key | ark:/13960/t0zp8zd9q |
| Language | English |
| Publisher Date | 1994-11-01 |
| Access Restriction | Open |
| Subject Keyword | Fluid Mechanics And Heat Transfer High Reynolds Number Viscosity Flat Plates Computational Fluid Dynamics Finite Difference Theory Wall Flow K-epsilon Turbulence Model Boundary Conditions Computational Grids Velocity Distribution Velocity Errors Boundary Layer Flow Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Technical Report |
