Temporal design of flow intermittency in grooved channel for advanced heat transfer enhancement

Abstract

The present numerical work is a continuing exploration of heat transfer enhancement by flow intermittency in grooved channels based on the energy buffer mechanism elucidated in our previous study, and aims to quantitatively optimize the time domain design of the intermittency pattern. The open-source computational fluid dynamics code OpenFOAM is employed to resolve the intermittent channel flow with triangular surface grooves. The main conclusion is that the optimal thermal performance is achieved when the time duration of each intermittency stage (acceleration, pulse-on, and deceleration) matches the characteristic time of flow dynamics (vortex development and heat transportation). The averaged surface Nusselt number is increased by 120% under the optimized intermittency pattern with the thermal performance factor reaching 1.9. The pulse-off stage of the flow intermittency expands further flexibility to meet diverse prerequisites in practical applications (constant coolant consumption, energy cost, or cooling capacity). By revealing the characteristic flow physics that governs the thermal performance of intermittent flow in grooved channels, the present work novelly proposes quantitative guidance on the temporal design of flow intermittency to achieve effective heat transfer enhancement.