Convective heat transfer due to an impinging synthetic jet: A numerical investigation of a canonical geometry

In the present study, a canonical geometry has been created for investigating the flow and heat transfer of a purely oscillatory jet that is not affected by the manner in which it is produced, and hence has allowed us to investigate the flow and heat transfer in a generalized approach. The unsteady Navier- Stokes equations and the convection-diffusion equation were solved using a full unsteady, two-dimensional finite volume approach in order to capture the complex time dependent flow field produced by periodic ejection-suction at high frequencies. The effect of the Reynolds number Re and the jet-to-surface distance H upon the heat transfer were parametrically examined, over a range of oscillation frequencies. Results were compared with a steady, laminar impinging jet of the same configuration, and over the same range, for matched Reynolds numbers Re <; 600. It was found that synthetic and continuous jets are comparable in cooling efficiency, but have dissimilar dependence on jet-to-surface distance. Furthermore, an optimum jet-to-surface distance was indentified for oscillatory jets that does not exist for steady laminar jets.