Numerical study of heat transfer augmentation of viscous flow in corrugated channels

The convective heat transport characteristics of subcritical and supercriti cal flows in periodic two-dimensional corrugated channels ala investigated numerically using the spectral element method. Computations were performed in the Reynolds number range of 50-800 and Prandtl number of 1, for corruga tion angles of gamma = 20 degrees and gamma = 30 degrees, and for wall spac ing-to-periodicity length ratio of b/L = 0.15-0.4. The critical Reynolds nu mber for onset of time-periodic, self-sustained oscillatory state decreases with increasing corrugation angle and with decreasing b/L ratio. The natur al frequency of these oscillations is computed, and it corresponds to the l east stable subcritical mode (Tollmien-Schlichting frequency) compatible wi th the given periodic geometry. The transport of heat heat and momentum due to the supercritical steady per iodic states in the corrugated channel are investigated and the relevant ti me- and space-averaged Nusselt number and friction factor are calculated. T he heat transfer of the corrugated channel increases as much as 120% when c ompared to a straight parallel channel at the same Reynolds number An optim al geometric ratio of b/L is also found, where a distinct maximum of the ra tio of heat removal rate to the normalized pressure drop is obtained.