格子ボルツマン法による不規則粗面壁の乱流熱流動解析

抄録

Skin friction and heat transfer augmentations due to the wall-roughness are discussed by means of the lattice Boltzmann direct numerical simulation of turbulent heat transfer over systematically varied irregular rough surfaces. The D3Q27 multiple-relaxation-time lattice Boltzmann method and D3Q19 regularized lattice Boltzmann method are respectively used to solve time-dependent flow and scale fields. The friction Reynolds number is fixed to 450, the skewness of the surface elevation and the effective slope of the surface elevation are varied to discuss a relation between the surface topology and the friction/heat transfer augmentations. The heat transfer and skin friction are increased by increasing the skewness and effective slope, which substantiates the augmentation effects due to the steep and peak-dominated rough surface. Although the wall-roughness increases both the skin friction and heat transfer, the augmentation of the heat transfer is smaller than that of the skin friction, indicating that the Reynolds analogy does not hold for the presently considered surfaces. The beak down of the Reynolds analogy is found to be more noticeable with increasing the roughness effects.