부산대학교 도서관

Direct numerical simulations of turbulent heat transfer over walls with mono- and multi-scale hemispherical roughness were carried out to explore how the roughness structure affects turbulent heat transfer. The friction Reynolds number was fixed at 150, 300, 600. The Prandtl number was 0.71 assuming an air flow. In this study, it is found that, provided that the ratios of the surface area to the surface area before adding the roughness, the relation between the temperature roughness function and the inner-scaled equivalent roughness is found to be consistent. A comparison with the DNS data in the literature suggests that the surface area ratio affects the temperature roughness function.