ACCURACY OF THE FLOW FIELD AROUND A CYLINDER FROM VARIOUS IMMERSED BOUNDARY FORMULATION

Calculating the flow field with complex geometry is one of the essential features of computational fluid dynamics. For finite volume formulation, a body fitted grid was usually utilized for such geometry. However, the immersed boundary method has become very popular these days since it can be applicable to a simple Cartesian coordinate system which uses finite difference schemes. It becomes much more effective along with two-phase flow modeling which is using continuous surface tension source formulation (CSF). There are several options for the immersed boundary techniques. Here, we are focused on the direct forcing method which is basically a ghost type approach. We tried to check the accuracy depending on forcing methods. Several forcing methods have been tested including linear velocity interpolation, stepwise or heaviside velocity filtering for the ghost nodes. We also tested a volume weighted velocity filtering approach for increased accuracy. For the benchmarking test, a flow field around the cylinder has been selected for comparison of the accuracy of different formulations.