Mixed Convection Dynamics of Newtonian Fluids from in-line Tube Banks Geometry

Abstract

This numerical study examines the mixed convection dynamics of Newtonian fluids through the in-line tube bank geometry using the commercial CFD solver ANSYS FLUENT under the aiding buoyancy conditions. Particularly, the arrays of circular cylinders have been used for the transverse flow of Newtonian fluids in the square geometrical arrangement. The momentum and heat transfer phenomena with technically significant geometries has been investigated for the following dimensionless parameters: solid volume fractions (es); 0.20 ≤ es ≤ 0.30, Reynolds number (Re); 50 ≤ Re ≤ 100, Prandtl number (Pr): 0.71≤ Pr ≤ 7 and Richardson number of Ri=1 and 2. The qualitative features have been explained in terms of contours of streamlines and isotherms and found influenced greatly with above governing parameters. The intense and swirled streamlines and isotherm patterns were observed with the enhanced Reynolds, Prandtl and Richardson numbers for every solid volume fractions. Besides, with increasing inertial effects, the wakes and vortex formations were also appeared behind the two periodic cylinders. The quantitative features have been displayed in terms of drag coefficients (individual and total) and the mean Nusselt number for the flow and the thermal features, respectively. Both individual and total drag coefficients are found to be decline with the increasing value of Reynolds number, whereas an increasing value was noticed with increase in Prandtl and Richardson numbers. The strong impact of solid volume fractions was also noticed on drag coefficients and found to be enhanced with increase in solid volume fractions. Further, an enhancement in the mean Nusselt number was also noticed with rise in Reynolds, Prandtl and Richardson numbers for a given solid volume fractions. In fact, the more resistance to flow in terms of drag coefficients was observed when the cylinders were closer and accordingly the heat transfer was also improved. Overall, an improvement in both momentum and thermal characteristics was found under the aiding buoyancy conditions for the parameters considered in this study.