Modeling rough stenoses by an immersed-boundary method

A pulsatile laminar flow of a viscous, incompressible fluid through a stenosed artery was simulated by an immersed-boundary method. The method allows the use of a simple (rectangular) computational domain in order to simulate a flow around a complex geometry obstacle with surface irregularities (roughness). The influence of the shape and the surface roughness on the flow resistance was explored. The obtained numerical results were validated by comparison with published experimental and numerical results. We show that the surface irregularities have no significant influence on the flow resistance across an obstacle for a physiological range of Reynolds numbers. Notwithstanding, an accurate representation of irregularities allows investigation of the near-wall effects of a realistic flow such as fluid recirculation. We show that a detailed study of flow patterns in the immediate vicinity of the irregular surface can be performed using the immersed boundary method.