Unsteady Vortex Dynamics of Two-Dimensional Pitching Flat Plate Using Lagrangian Vortex Method

Abstract

Vortex dynamics of wakes generated by two-dimensional rectangular pitching flat plates in free stream are examined with direct numerical simulation using Lagrangian vortex method. The developed method simulates external flow around complex geometry by tracking local velocities and vorticities of particles, introduced within the fluid domain. The viscous effect is modeled using a core spreading method coupled with the splitting and merging spatial adaptation scheme. The particle's velocity is calculated using Biot-Savart formulation. To accelerate computation, Fast Multipole Method (FMM) is employed. The solver is validated by performing an impulsively started cylinder at Reynolds number 550. The results of the computation have reasonable agreement with references listed in literature. For the vortex dynamics of pitching flat plate, the detaching LEV creates a remarkable peak in the lift force before the end of motion for the different pitching cases. For the low Reynolds number, force generated by the pitching flat plate is fairly independent of Reynolds numbers. The current studies also observed that TEV produced at higher Reynolds number has a stronger suction than that at smaller Reynolds numbers.