Woven structures are often used for separation of solid particles. The solid phase is separated when the fluid flows through the woven structure. Knowing the nature of the flow can be profitably used for the optimization of these structures (e.g., reduction of the pressure loss) and to predict the separation efficiency. In general, computational fluid dynamics allows the calculation of the flow field. In this paper, the immersed boundary method is shown as an efficient way to simulate the flow field within woven structures and reduce modeling efforts compared to the standard CFD method.