Direct numerical simulation study on the scaling for turbulent heat transfer over three-dimensional sinusoidal rough surfaces

Abstract

To discuss the effect of the wavelength of surface undulation on the turbulent heat transfer，we perform direct numerical simulations of turbulent heat transfer over three-dimensional sinusoidal surfaces with different wavelength of surface undulation．The friction Reynolds ranges from 180 to 600，and the Prandtl number is set to 0.7．The sinusoidal roughness enhances both the momentum and heat transfer; however，the enhancement of the momentum transfer is found to be lager．This unfavorable dissimilarity strongly depends on wavelength and Reynolds number．The temperature roughness function, which quantifies the augmentation of heat transfer, is found to increase with decreasing the mean wavelength．