Development of a Two-Dimensional CFD Code to Simulation of a Flapping Foil Problem at Low Reynolds Numbers

A computational fluid dynamic (CFD) code has been developed for simulation of two-dimensional flapping foil problem. Viscos flow has been simulated in an arbitrary Lagrangian-Eulerian description and a high quality mesh deformation technique used for modifying of the grid structure. The abilities of code is verified in compare of other references values and a good agreement with other numerical results has been observed. Structures of vortices are simulated and effect of them in leading and trailing edge regions on the thrust generation is investigated. The mechanism of thrust generation in flapping foil is attended and observed that it works based on exhaust of momentum, look like other propulsion systems. A mean flow, which has averaged during 20 period of oscillation, showed the accelerating of flow behind the foil and resemblance of the flow pattern with a jet flow. But flapping foil in contrast to jet flow has an unsteady inherent.