ISSN Online: 2377-424X
ISBN Print: 978-1-56700-474-8
ISBN Online: 978-1-56700-473-1
International Heat Transfer Conference 16
REYNOLDS ANALOGY IN TURBULENT FLOWS OVER ROUGH WALLS − A DNS INVESTIGATION
要約
Direct numerical simulation (DNS) of turbulent flow and heat transfer in rough channels with systematically varied roughness geometries is carried out in order to study the effect of roughness geometry on the Reynolds analogy factor (two times Stanton number divided by friction factor). The roughness samples are generated by a random distribution of roughness elements with different sizes on a flat surface. Effects of two important geometrical factors, the slope and the density of the roughness elements, are studied. All simulations are run at
a constant friction Reynolds number equal to 500. The results show that with an increase in the slope, Nusselt number increases while Reynolds analogy factor RA decreases. For varying roughness density, it is found that there exists a maximum value of Nusselt number and a minimum value of RA at certain roughness densities.