Effect of Cross Thermal Buoyancy on Cu–H2O Nanofluid Flow Over Bluff Objects at Low Reynolds Numbers

Abstract

Increasing the solid volume fraction (φ) in a nanofluid may trigger the vortex shedding around a bluff object even for a low Reynolds number (Re) steady regime. The cross thermal buoyancy may also trigger the vortex shedding around bluff objects at low Re. When the nanofluid flow is subjected to cross buoyancy, the initiation of the vortex shedding process around bluff objects could be accelerated. For a given range of Re, thermal buoyancy and solid volume fraction decide the characteristics of the flow. Both these two parameters can separately have a critical value at which the shedding process initiates. However, the presence of one parameter could affect the other significantly. In order to substantiate the above facts, a two-dimensional numerical simulation is performed to study the effect of cross thermal buoyancy on the free stream nanofluid (Cu–H2O) flow over two-dimensional square and circular cylinders. The initiation of the shedding process is observed for 10 ≤ Re ≤ 30 and 0% ≤ φ ≤ 10% through computation of the critical Richardson numbers for all the φ in the range. The relevant flow and thermal parameters are also computed to further establish the facts.