Interaction of freestream turbulence and surface roughness in separation-induced transition

This study explores how distributed surface roughness influences separation-induced transition on a flat plate, under the influence of freestream turbulence and adverse pressure gradients. Using direct numerical simulations, the interactions between freestream perturbations and vortices generated by roughness elements are investigated. Results reveal that low roughness accelerates instability development without dominating the transition process, while higher roughness causes a more intensified vortex mixing process and directly results in transition to turbulence.