Utilizing piezoelectric fan for heat transfer enhancement on corrugated surfaces

A numerical investigation is performed to explore the thermal-fluid characteristics of corrugated surfaces with different wave shapes cooled by a vibrating piezoelectric fan. Totally-nine different corrugated surfaces and one baseline flat surface are taken into consideration. Meanwhile, two non-dimensional parameters (A* and T*, representing the amplitude and period of the waves, respectively) are defined to describe the geometric char-acteristics of these corrugated surfaces quantitatively. Then the effects of A* and T* on flow heat transfer characteristic are investigated in detail. Time-averaged Nusselt number and instantaneous velocity vector are calculated. It is confirmed that the time-averaged Nusselt number distributions on corrugated surfaces is pri-marily determined by its geometrical shape, and the minimum and maximum values usually appear at the trough and peak, respectively. Compared to that of the flat surface, the corrugated surfaces could trigger the velocity boundary layer separation more easily, and the size of the corrugation directly limits the scale of the counter-rotating vortices. Of all these corrugated surfaces we studied, only the one with the smallest A* of 0.0625 and the largest T* of 2.0 is demonstrated advantageously. It is revealed that the wave shape influences the flow and heat transfer performance substantially.