Separating, transitional flow affected by various inflow oscillation regimes

Abstract

Consider the direct numerical simulations of laminar separation bubble flow with oscillating oncoming flow. We explore the influence of the amplitude and the period of the inflow oscillation on the dynamics of the separation bubble. The oscillating inflow causes the location of separation and the location of transition to alternately move upstream and downstream. For all simulations, in every period a new separation bubble is formed as the inflow decelerates. The growth-rate of the triggered Kelvin--Helmholtz instability depends on both the amplitude and the period of the inflow-oscillation.