Flow Past Stationary and Oscillating Airfoil at Low Reynolds number Using Sharp Interface Immersed Boundary Approach

Abstract: The present study reports on flow past airfoils (stationary and moving) using sharp interface immersed-boundary approach. Non-boundary conforming approach like immersed-boundary method offers a viable alternative over traditional boundary conforming approach by allowing us to model flow past arbitrarily complex shapes, by eliminating the need to re-grid the flow domain as the body exhibits motion. We present flow past a NACA 0012 airfoil at stationary conditions as well as exhibiting pitching motion. Evolution of vortex dynamics and wake structures are presented to show that the developed sharp interface immersed-boundary approach captures the flow physics of dynamic stall accurately. Moving body problems involving immersed-boundary approach usually encounter the issues of spurious oscillations and mass conservation. This is handled through a field extension strategy based on ghost cell approach, which allows for extrapolating the flow field value onto the ghost nodes, ensuring smooth temporal transition as the immersed surface moves through time. The results presented here show excellent agreement with the experimental results found in the literature.