Turbulent heat and momentum transport on a rotating disk

Measurements in the turbulent momentum and thermal boundary layers on a rot ating disk with a uniform heat flux surface are described for Reynolds numb ers up to 10(6). Measurements include mean velocities and temperatures, all six Reynolds stresses, turbulent temperature fluctuations, and three turbu lent heat fluxes. The mean velocity profiles have no wake region, but the m ean temperature profiles do. The turbulent temperature fluctuations have a large peak in the outer layer, and there is a third turbulent heat flux in the cross-flow direction. Correlation coefficients and structure parameters are not constant across the boundary layer as they are in two-dimensional boundary layers (2DBLs), and their values are lower. The turbulent Prandtl number agrees with 2DBL values in the lower part of the outer region but is reduced from the 2DBL values higher in the boundary layer. In the outer re gion of the boundary layer, the transport processes differ significantly fr om what is observed in two-dimensional turbulent boundary layers: ejections dominate the transport of momentum while both ejections and sweeps contrib ute to the transport of the passive scalar.