Numerical Investigation of Thermal Performance of Minichannels With Transversely Patterned Nonslip and Superhydrophobic Surfaces in Turbulent Flow Conditions

Abstract

The study aims at understanding the effects of transversely patterned nonslip and slip (superhydrophobic) surfaces on thermal performance and pressure drop in a circular minichannel under turbulent flow conditions. Numerical simulations of fluid flow through patterned minichannels for a Reynolds number of 5600 under constant heat flux conditions were performed using CFD software Star-CCM+. The κ–ω SST turbulence model with a coupled solver was used for simulating flow through the minichannels. Several numerical cases were simulated to understand the effects of nonslip to slip ratio and width of nonslip bands on pressure drop and thermal performance of circular minichannels. Two nonslip to slip ratios (1 and 1/3) and three different nonslip bandwidths (0.2δ, 0.4δ, 0.8δ) were considered in the simulation process. Parameters representative of the flow and heat transfer behavior such as boundary layer thickness, friction factor, slip velocity, shape factor, Nusselt number, and performance evaluation criterion (PEC) were calculated to better understand the effects of nonslip to slip ratio and width of nonslip bands on thermal performance. The simulation results reveal that a decrease in nonslip to slip ratio and increase in nonslip width lead to a reduction in pressure drop and an enhancement in heat transfer. Furthermore, the configuration with a nonslip to slip ratio of 1/3 and a nonslip width of 0.8δ was found to be the optimal minichannel design, achieving a 40% reduction in pressure drop with a PEC value of 3.4. In summary, the numerical simulations show that properly designed microchannels consisting of slip and nonslip bands arranged transversely to the flow direction can lead to enhanced thermal performance under turbulent flow conditions.