Transient mixed convection in a two-sided lid-driven differentially heated square cavity utilizing nanofluids

Abstract

Transient behaviour of mixed convection inside a two-sided lid-driven differentially heated square cavity filled with nanofluids is investigated numerically to gain insight into convective recirculation and flow processes evolved with time. A model is developed to analyse the behaviour of nanofluids taking into account the solid volume fraction (χ). The transport equations are solved numerically using the finite volume approach and a SIMPLE algorithm on a non-staggered grid with deferred QUICK scheme. Comparisons with previously published work are performed and found to be in excellent agreement. The solution procedure is moved with small values of τ so that a transient behaviour can be captured. Richardson number, Ri = Gr/Re2, a measure of relative importance of natural and forced convection modes on the heat transfer, is taken as 1 so that the phenomena of mixed convection can be understood effectively. Copper-water nanofluid is used with Pr = 6.2 and solid volume fraction χ is varied as 0.0, 0.08, and 0.16. Detailed results are presented for streamline and isotherm patterns. A comparison of average Nusselt number shows that heat transfer is more in the case of χ = 0.16. The present study focuses on the transient analysis of several parameters on the heat transfer characteristics of nanofluids within the enclosure.