Effect of third size on natural convection of variable viscosity fluid in a closed parallelepiped

Thermal convection is one of the main mechanisms that are implemented in different cooling systems. Most often this phenomenon occurs in such practical areas as microelectronics, instrumentation and building construction. In this article, the numerical simulation of thermogravitational convection of medium having dependent viscosity inside closed enclosure with isothermal heating/cooling from vertical walls has been conducted. Other borders of the chamber are heat insulated. The control relations have been written employing non-dimensional vector potential functions, vorticity vector and temperature. The finite difference procedures are applied for solving of the considered differential equations. Obtained outcomes have been compared with numerical data for thermal convection within a differentially heated square cabinet. An influence of third coordinate, Rayleigh number and viscosity variation parameter on thermal distribution and flow structures combined with mean Nusselt number has been demonstrated. Obtained outcomes have shown that for the considered 3D problem an evaluation of the mean Nusselt number can be performed by employing 2D data when the aspect ratio is greater than or equal to unity.