Revisit on natural convection from vertical isothermal plate arrays II-3-D plume buoyancy effects

The three-dimensional characteristics of natural convection from isothermal vertical plate arrays with finite lengths are numerically analyzed. Studied are single- and multi-channel plate arrays with different plate length/height (L/H) ratios. To account for the extra plume buoyancy and the entrance flow resistance, extended computation domains encompassing the whole plate arrays are arranged. Highly non-uniform distributions of heat transfer coefficient exhibit along the plate, with the highest value at the plate end due to the effect of side flow. Inward, the heat transfer coefficient decreases drastically with boundary layer development but re-rises over the inner region as a result of higher plume buoyancy therein. As L/H increases, the stronger plume buoyancy promotes the overall heat transfer coefficient to approach the 2-D value with a difference of less than 4% when L/H ≥ 2. The extra plume buoyancy varies in different channels, weakest in the edge channel, leading to complex flow above the outermost channels. The plume-buoyancy enhancement on the overall heat transfer coefficient is less pronounced for arrays with finite L/H ratios than for a 2-D array due to the plume shrinkage associated with the side flow.