Numerical investigation of laminar jet arrays impinging onto dimpled target surface

The flow and heat transfer of three-by-eight laminar jet arrays impinging onto a dimpled surface with Reynolds number 100 in steady state have been investigated numerically in the present study. Grid independence was confirmed and good agreement was reached through comparison between the results obtained from the literature and the present work. The effect of jet-to-plate spacing (H/d = 1-10) dimple diameter (D_d/d = 2-4) and the dimple relative depth (δ/D_d = 0.10-0.30) on the flow and heat transfer characteristics of laminar impinging jet arrays was explored numerically. The average Nusselt number decreases with increasing jet-to-plate spacing, dimple relative depth, and dimple diameter. The jet flow in the downstream jets is deflected by crossflow, which makes low-velocity fluid appear in the corresponding dimples and the area is enlarged. Thus, the presence of dimples causes overall heat transfer deterioration in the laminar impinging jet arrays.