Obstacle arrangements effect on the mixed convection in an enclosure with movable top surface

The flow finds extensive application in coating, drying, and mixing processes. The temperature and velocity distribution inside a rectangular enclosure that is driven by a lid were examined using a finite volume numerical method. Five adiabatic cylindrical obstacles were mounted within the cage measures 25 cm in width and 30 cm in length. The right and left walls enclosure is each fully insulated, the top wall was cooled isothermally at Tc and moved at variable speed of U, and the bottom wall was kept at Th using water as a working fluid. Three types of an obstacle with equal area were utilized in this study they were, circle triangle and square. The results showed that the average Nusselt number increases by 10.4%,12%, 16%, and 19% compared with that of without the obstacle for radius values (r=0.5,1,1.5 and 2 cm) respectively. The results indicate that obstacles can be very useful in achieving a higher rate of heat transfer compared to the enclosure without obstacles. Also, as opposed to a situation without barriers, the results demonstrate that the existence of obstructions causes an increase in the average Nusselt number. When compared to triangular and square shapes, the obstacle with a circular shape has a larger average Nusselt number. Furthermore, the enhancement percentage of Nusselt number was calculated to be 16, 13, 11 % for obstacle models of circle have a radius of 1 cm, triangle and square of 1 cm (major dimension) respectively comparing with that of no obstacles.