Physics Based Simulation of Reynolds Number Effects in Vortex Intensive Incompressible Flows

摘要

An understanding of Reynolds number effects is essential for extrapolating model- or quarter-scale results to full-scale. The state-of-the- art in the prediction of full-scale maneuvering performance utilizes a combination of experience, heuristics, and empiricism. To better understand these scale effects, it would be ideal to validate the flow solver at full-scale Reynolds numbers. However, the preponderance of experimental data available for undersea vehicles is limited to model-scale. The unavailability of full-scale data prevents a thorough validation of the high Reynolds number capabilities, but basic validation can be achieved using flat plate boundary layer results and Reynolds number scaling. This study investigates the differences in the computed flow fields between model-, quarter-, and full-scale Reynolds numbers. Towards this end, an efficient RANS incompressible flow solver, U2NCLE, which is capable of performing viscous high Reynolds number flow simulations for complex geometries using unstructured grids, has been developed. This flow solver is to be demonstrated for large-scale meshes with good sub-layer resolution (y(exp +) < 1) and approximately 10(exp 6) points or more with an emphasis toward hydrodynamic applications. Results are shown for model-, quarter-, and full- scale computations on the SUBOFF model with sail at various angles of drift. Effects of grid density on computed flow fields at model-scale and full-scale Reynolds numbers also are considered. (13 figures, 10 refs.).