Experimental investigation of mixed convective flow over a wavy wall

An experimental study is carried out to address mixed convection from a heated wavy surface. The channel flow between the sinusoidal surface and a flat top wall is investigated by means of a combined digital particle image velocimetry (DPIV) and planar laser-induced fluorescence (PLIF) technique to examine the spatial variation of the streamwise and wall-normal velocity components, and to assess the concentration field of a tracer dye injected into the fluid. We discuss the influence of mixed convection on turbulence quantities and scalar transport properties. Due to the influence of mixed convection we find asymmetric mean velocity profiles and increased momentum transport in the vicinity of the heated surface. The transport of the tracer dye is characterized by enhanced vertical transport due to buoyancy effects and enhanced spanwise transport due to the presence of longitudinal flow structures induced by the mixed convection. We identify two dominant scalar structures with the most influence on vertical transport. The first one is induced by buoyancy effects, the second one by a combination of buoyancy effects and local wall curvature. Thus the transport properties are additionally enhanced compared to mixed convection from a flat plate by the presence of the wavy surface.