Boundary Condition Models for Synthetic Jet Simulation

Abstract

Flows induced by synthetic jets have been computed by solving two-dimensional unsteady preconditioned Reynolds Averaged Navier-Stokes equations with four boundary condition models for synthetic jets. A transparent jet boundary model mimics the synthetic jet by specifying fluid velocity at the fictitious inflow boundary. Two simple periodic boundary condition models specify the velocity profiles either at the exit of the synthetic jet or at the diaphragm. In an exact jet model for the synthetic jet, the flow induced by a net flux zero jet is computed by including the movement of a diaphragm into flow computation. To accurately capture the physics of the synthetic jet with the exact jet model, the geometric conservation law (GCL) has been employed which accounts for the volumetric change of computational cells. Numerical calculations along with the transparent boundary model, two simple periodic boundary conditions, and the exact jet model have been carried out for two synthetic jet configurations into quiescent air; case 1 of CFDVAL2004 workshop and the experimental study conducted at Seoul National University. Computational results for four jet boundary models indicate that the exact jet model is capable of producing accurate results without modeling velocity profile.