Unsteady buoyancy-driven heat transfer enhancement of nanofluids in an inclined triangular enclosure

Heat transfer enhancement in a two-dimensional inclined lid-driven triangular enclosure utilizing nanofluids is investigated numerically for various pertinent parameters. The present model is developed to analyze unsteady heat transfer performance of nanofluids inside an enclosure taking into account the solid volume fraction δ, variable velocity and variable thermal boundary conditions. Fluid mechanics and conjugate heat transfer described in terms of continuity, linear momentum and energy equations. The transport equations are solved numerically using the Galerkin finite element method. Results are obtained for a wide range of parameters such as the Grashof numbers (103 ≤ Gr ≤ 106), and time step (0.01 ≤ τ ≤ 1). Copper-water nanofluids is used with Prandtl number, Pr = 6.2 and solid volume fraction δ is varied from 0% to 25%. The streamlines, isotherm plots and heat transfer correlation of the average Nusselt number at the hot surface as well as average fluid temperature in the enclosure is presented and discussed in detail. It is found that heat transfer increased by 31.85% as volume fraction δ increases from 0% to 25% at Gr = 105 for τ = 0.01. Moreover, the variation of the average Nusselt number and average fluid temperature in the cavity is linear with the solid volume fraction.