Numerical modelling of bubble growth in microchannel using Level Set Method

Development of more efficient thermal management systems is of prime importance not only in the context of environmental and energy concerns, but also due to ever-increasing demands of computational power. Flow boiling in microchannels holds a lot of promise and is capable of removing high heat fluxes. However, the physics behind the heat transfer and fluid flow during flow boiling at micro scales is not completely understood. Various studies have been performed to classify the flow regimes and identify the dominant mode of heat transfer in two phase flow through microchannels. In the present work, a numerical study is performed to investigate the bubble dynamics in a confined microchannel. A DGLSM (Dual-Grid Level Set Method) based numerical model is used to capture the unsteady bubble interface dynamics. The Navier-Stokes equation is being solved using Finite Volume Method (FVM) based Semi-Explicit Pressure Projection Method. The effect of parameters namely contact angle, surface tension, wall superheat, Reynolds number and system pressure on the bubble dynamics and bubble growth rates is investigated. Three distinct stages of heat transfer corresponding to the rapid reduction, stabilization and enhancement of evaluated Nusselt number are identified from the parametric investigation. The results show that the system pressure plays a vital role in controlling the bubble shape, as compared to remaining parameters. (C) 2016 Elsevier Ltd. All rights reserved.