Application of Radial Based Function for Overset Grid Interpolation in naoe-FOAM-SJTU Solver

Overset technique have been used for many sectors in computational fluid dynamics due to the flexibility they afford for handling complex geometries and simulations involving bodies with relative motion such as propeller, rotorcraft, and wind turbine configurations. However, it also gives rise to some numerical problems, such as the violation of mass conservation due to the interpolation error. At the overlapping region, the conservation error will give an additional source on Poisson equation, which will lead to the pressure fluctuation. For the case where the flow induced pressure fluctuation is particularly interested such as vortex induced vibration, tip vortex shedding from the propeller by using naoe-FOAM-SJTU solver, the conservation error will pollute the desired frequency or flow structure.

In this study, the conservation error is minimized by enforcing flux correction and using higher order interpolation scheme (radial based function) to improve the CFD solver naoe-FOAM-SJTU. The results show that enforcing flux correction do not have considerable effect on minimize the force fluctuation, but the improvement can be observed in the pressure contour. The RBF based interpolation are compared with the clipped Laplacian and least squared scheme by conducting a simulation of oscillating cylinder. Numerical test reveals that the drag coefficient is highly oscillatory for all case except for RBF method.

In this study, the conservation error is minimized by enforcing flux correction and using higher order interpolation scheme (radial based function) to improve the CFD solver naoe-FOAM-SJTU. The results show that enforcing flux correction do not have considerable effect on minimize the force fluctuation, but the improvement can be observed in the pressure contour. The RBF based interpolation are compared with the clipped Laplacian and least squared scheme by conducting a simulation of oscillating cylinder. Numerical test reveals that the drag coefficient is highly oscillatory for all case except for RBF method.