ABSTRACT

The dynamics of the velocity and surface pressure fields in the recirculating regions upstream of the foot of a forward-facing step and downstream of the step corner are investigated experimentally for a thin turbulent oncoming boundary layer at a Reynolds number, based on the step height, of 10⁵. Velocity measurements are acquired concurrently in the upstream and downstream regions of the step using Particle Image Velocimetry (PIV) and synchronized with time-resolved wall-pressure measurements acquired at 20 locations on the front and top walls of the step. A multitime-delay linear stochastic estimation is employed to reconstruct time-resolved PIV snapshots to reveal the nature of the connection between the upstream and downstream recirculating regions. It is shown that the complex dynamics of the upstream recirculating bubble is imprinted onto the separated flow region on the top of the step.