Numerical investigation of natural convection in two enclosures separated by anisotropic solid wall

Abstract

Purpose – The problem of natural convection in two cavities separated by an anisotropic central solid wall is considered numerically. When the thermal conductivity of the central wall is anisotropic, heat flux and temperature gradient vectors are no longer coincidence. This apparently has interesting influences on the heat and fluid flow patterns in this system. The paper aims to discuss these issues. Design/methodology/approach – In this work, several flow patterns have been investigated covering a wide range of Rayleigh number up to 108. Several thermal conductivity anisotropy scenarios of the central wall have been investigated including 0, 30, 60, 120 and 150° principal anisotropy directions. The governing equations have been solved using control volume approach. Findings – Probably the most intriguing is that, for some anisotropy scenarios it is found that the temperature at the same elevation at the side of the central wall which is closer to the colder wall is higher than that at the side closer to the hot wall. Apparently this defies intuition which suggests the reverse to have happened. However, this behavior may be explained in light of the effect of anisotropy. Furthermore, the patterns of streamlines and temperature fields in the two enclosures also changes as a consequence of the change of the central wall temperatures for the different anisotropy scenarios. Originality/value – This work discusses a very interesting topic related to heat energy exchange among two compartments when the separating wall is anisotropic. In some anisotropy scenarios, this leads to more uniform distribution of Nusselt number than the case when the wall is isotropic. Interesting patterns of natural convection is investigated.