Flow and Thermal Characteristics of Jet Impingement on a Dimple Plate Using Large Eddy Simulation

Abstract

AbstractA round turbulent air jet is impinging on heated plate and is numerically analyzed by large eddy simulation (LES) at the plate to nozzle spacing, h/Dj = 2(where Dj is jet diameter), Reynolds number (Rej) = 5000, and diameter ratio (D/Dj) = 0.318 (where D is dimple print diameter), and relative depth (δ/Dj = 0.3) (where δ is dimple depth) for concave and convex dimples and is used in the present study, LES, consider sub-grid scale (SGS) model, i.e., Wall Adaptive Local Eddy viscosity (WALE). Averaging in space and time is performed to give information of mean velocity in stagnation and wall jet regions. Various important dynamical stream structures have been visualized from the instantaneous data obtained from LES. The local Nusselt number, mean velocity, and coefficient of pressure are calculated for both configration of dimples. Various flow phenomena such as flow separation and reattachment are represented and their effect on heat transfer phenomenon are explained. Vorticity contours were in good resemblance with experimental results (Terekhov et al., Impingement of an impact jet onto a spherical cavity. Flow structure and heat transfer. Int J Heat Mass Transfer 52:2498–2506, 2009; Kanokjaruvijit and Martinez-botas, Int J Heat Mass Transfer 48:161–170, 2005). Results obtained from WALE sub-grid scale model are in good accordance with experimental results.KeywordsLarge eddy simulation (LES)WALE sub-grid modelConcaveConvex dimple