Numerical simulation of natural convection using unsteady compressible Navier-stokes equations

Abstract

Purpose Boussinesq approximation is widely used in solving natural convection problems, but it has severe practical limitations. Using Boussinesq approximation, the temperature difference should be less than 28.6 K. The purpose of this study is to get rid of Boussinesq approximation and simulates the natural convection problems using an unsteady compressible Navier-Stokes solver. The gravity force is included in the source term. Three temperature differences are used namely 20 K, 700 K and 2000 K. Design/methodology/approach The calculations are carried out on the square and sinusoidal cavities. The results of low temperature difference have good agreement with the experimental and previous calculated data. It is found that, the high temperature difference has a significant effect on the density. Findings Due to mass conservation, the density variation affects the velocity distribution and its symmetry. On the other hand, the density variation has a negligible effect on the temperature distribution. Originality/value The present calculation method has no limitations but its convergence is slow. The current study can be used in fluid flow simulations for nuclear power applications in natural convection flows subjected to large temperature differences.

Moist Air Flow Analysis in an Open Enclosure. Part A: Parametric Study

“…Thereby, these heat and concentration gradients are considered to assist or oppose the performance of a system, depending on the boundary conditions of a problem. Many researchers tried to analyze extensively solutions on the heat transfer flow within closed or open cavities [10][11][12][13][14][15][16][17]. Some studies used heat flux or temperature gradient fields to the cavity walls as boundary conditions [18][19][20].…”

The impact of heterogeneous anisotropy of porous media on density-driven convection

“…On the other hand, numerical simulation is also widely employed to study the similar convection flow (Lewis and Schrefler, 1998; Lewis et al , 2004), e.g. heat and mass transfer in natural convection (El-Gendi and Aly, 2017; Nguyen et al , 2018; Shahsavar et al , 2019; Aliakbarzadeh et al , 2019), multiphase flow in oil reservoirs (Pao et al , 2001; Lewis and Pao, 2002; Pao and Lewis, 2002; Lewis et al , 2003; Masters et al , 2000) and double-diffusive convection (Peterson et al , 2010; Lewis and Sukirman, 1993). In addition, by solving Darcy’s equations, density-driven miscible flow in porous media had also been intensively simulated (Riaz et al , 2006; Ghesmat et al , 2011).…”