Suppression of flow separation of power-law fluids flow around a confined circular cylinder by superimposed thermal buoyancy
Keywords:Power-Law fluids, Steady flow, Thermal buoyancy, Flow suppression, Nusselt number Heat transfer, Critical Richardson number.
This paper presents a comprehensive computational work on hydrodynamic and thermal phenomena of flow separation around a confined circular cylinder by superimposed thermal buoyancy. For that purpose, let us consider a confined flow of Non-Newtonian power-law fluid around a heated circular cylinder in a two-dimensional vertical channel. The effects of thermal buoyancy and power-Law index on the flow separation and the average Nusselt number are studied for the conditions: (10 ≤ Re ≤ 40), (0.4≤ n ≤ 1.2), (0 ≤ Ri ≤ 0.8), Pr = 50 and blockage ratio β = 0.2. The Reynolds numbers of flow are chosen in low range such that the flow remains steady and separated without imposition of the thermal buoyancy. In the steady flow regime the results show that the augmentation of the power-law index in the absence of thermal buoyancy causes a separation to grow. The thermal buoyancy delays the separation in different power-law indexes gradually and at some critical value of the buoyancy parameter it completely disappears resulting a stuck flow around a cylinder. Moreover, the recirculation length and skin friction are calculated to support the above finding. The decrease in the power-Law index increases the heat transfer rate. The Nusselt numbers are computed to predict the heat transfer rates of power-law fluids under the superimposed thermal buoyancy condition.