Optimal position of square cylinder vortex generator in channel is not a function of ordinate only – A heat transfer and optimization study

Abstract

Wall heat transfer enhancement of a channel by introducing an adiabatic square cylinder as a vortex generator is investigated numerically and reported. An open-source computational fluid dynamics toolbox, OpenFOAM is used for the present numerical investigation where a base solver icoFOAM is modified by incorporating the energy equation for analyzing the heat transfer characteristics. The cylinder position; axial (in the direction of flow) and transverse (normal to the flow direction) both the locations are varied to analyze the effect of these parameters on the wall heat transfer performance of the channel. In addition, the effect of change of channel length and height along with Reynolds number on the heat transfer characteristics are investigated. The present result indicates that the position of an adiabatic cylinder for enhancing the wall heat transfer in a channel may not be presumed a priori. It is observed that axial and transverse location of cylinder has significant influence on the enhancement of heat transfer rate. An optimum location of cylinder is observed based on maximum Nusselt number. Further, the Nusselt number is noticeably affected by the channel length and height along with Reynolds number. Thus, the location of a cylindrical vortex generator in a channel needs to be optimized for maximum thermal performance and cannot be ascertained a priori. For this purpose, a correlation of thermal performance with cylinder location, channel dimension, and Reynolds number is presented in the present study, and then the optimized location of the adiabatic cylinder is found for maximum thermal performance by using Particle Swarm Optimization (PSO).