Flow Past Tandem Circular Cylinders at High Reynolds Numbers using Overset Grids in OpenFOAM

This study investigates the application of overset grids for simulating high Reynolds number flows in OpenFOAM. The problem of tandem cylinders is specifically chosen as an appropriate test model due to (a) a direct relevance to the marine industry and (b) the availability of experimental results conducted at the Basic Aerodynamics Research Tunnel at LaRC. Usage of overset grids in OpenFOAM has previously been demonstrated only using SUGGAR++, and this library is not easily available to the general public. This paper thus explores the application an in-house overset grid library (Overset Parallel Engine for Aerodynamics Applications) OPErA in OpenFOAM. For verification purposes of the overset coupling, results are presented for the inline oscillation of two cylinders in low Reynolds numbers Re 40. For the high Reynolds number case of Re 1.66×10, an assesment of the forces and the flow between the cylinders are presented for static tandem cylinders with a distance to diameter spacing of (L/D = 1.4). This specific spacing corresponds to a sub-critical spacing (short separation) where the drag on the rear cylinder is negative. For single grid computations, force predictions for (a) a non-linear URANS model and (b) a hybrid model are presented. For overset grid computations, only non-linear URANS results are presented to verify the implementation of the overset coupling. Comparisons between single grid and overset grid cases for the forces and the flow features are very encouranging and demonstrate greater potential in using overset grids for moving body problems.

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