On the stability of flows over rough rotating disks

We consider the effects of distributed roughness on the boundary-layer transition over a rotating disk using both theoretical and experimental approaches. The theoretical approach further develops Yoon et al.’s method [Int. J. Heat Fluid Flow, 28, p262 (2007)] for obtaining the steady-flow solutions for a general surface distribution function. Full threedimentional stability analyses are conducted on these for a range of roughness parameters. The experimental approach seeks to verify the steady-flow solutions and investigate the transition mechanisms at play with increasing surface roughness. Both approaches yield consistent results that suggest that surface roughness could lead to a transition mechanism that bypasses the usual cross-flow mechanism.