CFD analysis of twin turbulent plane jets confined by walls: Effects of geometry on flow dynamics and heat transfer

Abstract

This study investigates the flow and heat transfer behavior of heated twin turbulent plane parallel jets confined between isothermal walls. The focus is on understanding the impact of key geometric parameters: the separation ratio and offset ratio. While dual plane offset jets have been studied in various unconfined or isothermal configurations, the combined impact of heating, confinement and jet geometry remains insufficiently addressed in the literature. This work fills the gap by conducting a systematic analysis using two-dimensional Computational Fluid Dynamics simulations. Validation against experimental data for three different jet configurations showed good agreement with experimental data, with the SST k-ω model providing the most balanced performance out of four turbulent models tested. The results revealed that despite geometrical symmetry, the jets consistently deflect towards one of the walls due to the Coanda effect, leading to flow asymmetry and influencing heat transfer. An increase in the separation and offset ratios shifts the reattachment point downstream, weakens the intensity of wall impingement, and reduces local peak wall shear stress and the maximum local Nusselt number at the walls. Increasing the offset ratio from 2 to 5 enhanced average heat transfer at the jet impingement wall by 20%. Conversely, increasing the separation ratios from 2 to 5 decreased the average heat transfer to the opposite wall by 11% and to the impingement wall by 1%. These findings contribute to a better understanding of complex wall-jet interactions and support the design of thermal systems involving confined turbulent dual offset jets.