Direct numerical simulation of a short laminar separation bubble and early stages of the bursting process

Abstract

Direct numerical simulation of a pressure-induced short laminar separation bubble developing on a flat plate has been carried out. Transition in this bubble was triggered by small disturbance input with a fixed frequency and fixed spanwise wave number. The resulting short bubble was shown to be converged in time to a statistically steady state, while possessing essential features of short laminar separation bubbles as reported in the literature. In the present case disturbance input is required to maintain a short bubble. Switching off this disturbance input yields a growing separation bubble. This phenomenon is denoted as bubble bursting, since indication is found that the bubble develops towards a long-bubble state. © 2007 Springer-Verlag Berlin Heidelberg.