Unsteady Numerical Investigation Strategy of Natural Convection in an Isosceles Superimposed Triangular Enclosure

Abstract

In energy applications, convection plays a dominant role in the transport of energy for the proper design in order to achieve higher heat transfer rates. Where the fluid motion is simply induced by density gradients. This study is concerned with transient natural convection in an isosceles-superimposed triangular enclosure.  The inclination of the inclined partitions walls was θ =45°. Critical Rayleigh numbers have been obtained: Ra=10⁶, especially for the fluid crushed between the two triangles where we can visualize the critical convection transaction between the air and water. The results in quantitative measurement of average Nusselt number change and qualitative visualization of streamline and isotherms are examined. The air and water streamlines and the temperature fields were obtained for the Rayleigh numbers 10³ ≤ Ra ≤ 10⁸ for both cases studied. Besides, the highest heat transfer performance is observed during the natural convection case of the water fluid, and the lowest heat is transferred when the fluid is dilatant.  The triangular shape can greatly enhance the heat transfer from the bottom to the top at first in a smooth and harmonious manner, and then it turns into a more complex and disorderly shape when the water reaches high temperatures.