Forced convection in a square cavity with inlet and outlet ports

Abstract

A finite-volume-based computational study of steady laminar forced convection inside a square cavity with inlet and outlet ports is presented. Given a fixed position of the inlet port, the location of the outlet port is varied along the four walls of the cavity. The widths of the ports are equal to 5%, 15% and 25% of the side. By positioning the outlet ports at nine locations on the walls for Re = 10, 40, 100 and 500 and Pr = 5, a total of 108 cases were studied. For the shortest distance between the inlet and outlet ports along the top wall, a primary clockwise (CW) rotating vortex that covers about 75–88% of the cavity is observed. As the outlet port is lowered along the right wall, the CW primary vortex diminishes in strength, however a counter-clockwise (CCW) vortex that is present next to the top right corner grows in size. With the outlet port moving left along the bottom wall, the CW primary vortex is weakened further and the CCW vortex occupies nearly the right half of the cavity. The pressure drop varies drastically depending on Re and the position of the outlet port. If the outlet port is on the opposite or the same wall as the inlet, the pressure drop is smaller in comparison to a case where it is located on the adjacent walls. The maximum pressure drop occurs when the outlet port is on the left side of the bottom wall and the minimum is achieved where the outlet is on the middle of the right wall. Regions of high temperature gradient are consistently observed at the interface of the throughflow and next to the solid walls on both sides of the outlet port. Local Nusselt numbers are low at three corners when no outlet port is present in their vicinity, whereas intense heat transfer rate is observed on the two sides of the outlet port. Between these minima and maxima, the local Nusselt number can vary drastically depending on the flow and temperature fields. By placing the outlet port with one end at three corners, maximum overall Nusselt number of the cavity can be achieved. Minimum overall heat transfer of the cavity is achieved with the outlet port located at the middle of the walls. The case exhibiting maximum heat transfer and minimum pressure drop is observed when the outlet port is located at dimensionless wall coordinate (2 + 0.5 W).