Geometrical Evaluation of a Channel with Alternated Mounted Blocks under Mixed Convection Laminar Flows Using Constructal Design

Abstract: This work presents a numerical study of incompressible, laminar,two-dimensional, mixed convection flows in horizontal channels with tworectangular alternated blocks mounted in the surfaces. The influence ofthe geometry and positioning of the blocks on the heat transfer rate isevaluated using Constructal Design. The problem is subjected to twogeometric constraints associated with the areas of the channel and thetwo blocks and three degrees of freedom: H1/L1(the ratio of the height to the width of the upstream block),H2/L2(the ratio of the height to the width of the downstream block), andL3(the horizontal distance between the centers of the blocks). The purposeis to maximize the heat transfer rate per length unitq′considering three different Reynolds (ReH= 10 ,100, and 200) and Grashof numbers (GrH= 650 ,6,500, and 65,000). The conservation equations of mass, momentum, andenergy are solved using the Finite Volume Method, and the buoyanceforces are modeled with the Boussinesq approximation. In general, thebest performance is reached for the largest intrusion of the blocks.However, changes in GrHand ReHaffected the optimal distance (L3) o,and for GrH= 65 , 000 non-symmetrical blocks led to the best performance, showing theimportance of design investigation for different flow conditions.