A method for replicating ice accretion roughness using multi-scale analog distributions.

A new approach of creating an analog surface for a surface with natural roughness is presented based on the hypothesis that the dominant skin friction and heat transfer augmentation mechanisms are 1) the vortex shedding from the roughness elements and 2) the interaction of the shed vortices with the next downstream roughness elements. An autocorrelation function was employed on a real ice surface to capture the root-mean-square-roughness height, the primary streamwise wavelength, and the aspect ratio of surface microscales. Two distributions of deterministic roughness, one of ellipsoids and one of elliptical cones, were created to match the primary features of the real ice surface. This work describes the analog surface creation method and characterizes the convective enhancement and velocity boundary layer development of the analog surfaces. The convective enhancement and velocity boundary layer results associated with the analog surfaces are then compared to those of the real ice surface.