Hybrid nanofluid flow past a shrinking cylinder with prescribed surface heat flux

Abstract

his numerical study was devoted to examining the occurrence of non-unique solutions in boundary layer flow due to deformable surfaces (cylinder and flat plate) with the imposition of prescribed surface heat flux. The hybrid Al2O3-Cu/water nanofluid was formulated using the single phase model with respective correlations of hybrid nanofluids. The governing model was simplified by adopting a similarity transformation. The transformed differential equations were then numerically computed using the efficient bvp4c solver with the ranges of the control parameters 0.5% ≤ ϕ1, ϕ2 ≤ 1.5% (Al2O3 and Cu volumetric concentration), 0 ≤ K ≤ 0.2 (curvature parameter), 2.6 < S ≤ 3.2 (suction parameter) and -2.5 0) and a flat plate (K = 0) with the inclusion of only the suction (transpiration) parameter. The real and stable solutions were mathematically validated through the stability analysis. The Al2O3-Cu/water nanofluid with ϕ1 = 0.5% (alumina) and ϕ2 = 1.5% (copper) has the highest skin friction coefficient and heat transfer rate, followed by the hybrid nanofluids with volumetric concentrations (ϕ1 = 1%, ϕ2 = 1%) and (ϕ1 = 1.5%, ϕ2 = 0.5%), respectively. Surprisingly, the flat plate surface abates the separation of boundary layer while it enhances the heat transfer process.