Separated turbulent flow simulations using a Reynolds stress model and unstructured meshes

Numerical simulation of three-dimensional, separated, high Reynolds number turbulent flows is performed using a second-order accurate cell-centered finite volume method on unstructured meshes. The computations include an application of Reynolds Stress Modeling (RSM), which consists of coupling the Reynolds transport equations with the Favre averaged Navier-Stokes Equations. The resulting system of 12 coupled, non-linear partial differential equations is solved using PUMA RSM which is an in-house an unstructured grid computational fluid dynamics code written in ANSI-C++. Computations are performed on unstructured meshes composed of tetrahedral cells. In order to reduce the CPU time and memory requirements, parallel processing is applied with the MPI (Message Passing Interface) communication standard. The resulting parallel code is run on Beowulf clusters. Results for high Reynolds number flow around a 6:1 prolate spheroid and a sphere are presented and compared with experimental results. In the prolate spheroid case predictions of mean pressure and circumferential locations of cross flow separation points are in good agreement with experiment. The locations of primary and secondary separation points are computed with an error of roughly three degrees. Mean pressure and skin friction predictions for sphere solutions are also in good agreement with the measurements. The computed separation location is very close to the measured one. The distribution of turbulent stresses shows that the turbulent flow around a sphere is highly anisotropic and supports the notion that using anisotropic turbulence models are necessary for three-dimensional separated flows.