ANALYSIS OF THE EFFECTS OF MASS AND THERMAL STRATIFICATION ON NATURAL CONVECTION FLOW PAST A CYLINDER WITH VARIABLE THERMAL CONDUCTIVITY AND DIFFUSION COEFFICIENT

Abstract

This paper presents a comprehensive analysis of the effects of mass and thermal stratification by providing analytical solution for the unsteady, one-dimensional natural convection flow past an infinite vertical circular cylinder in a stably thermally stratified fluid medium, incorporating variable thermal conductivity and diffusion coefficients. The dimensionless coupled linear partial differential equations (PDE) governing the flow are solved using Olayiwola’s Generalized Polynomial Approximation Method (OGPAM) for different sets of physical parameters. The effects of these parameters are illustrated and discussed with the aid of graphs. The results show that mass and thermal stratification significantly influence the velocity, temperature, and concentration profiles of the fluid. Specifically, an increase in thermal stratification leads to a rise in the system’s temperature as Increased thermal stratification traps heat in the upper layers, reduces convective mixing, and suppresses cooling. Furthermore, as thermal diffusivity increases, fluid velocity decreases across the radial distance due to reduced buoyancy forces, producing a flatter and less pronounced velocity profile this is due to the fact that heat spreads faster, temperature gradients shrink, buoyancy forces weaken, and fluid motion slows down. This creates a lower and flatter velocity profile across the radial distance. Similarly, increase in mass stratification generates a concentration gradient which traps solute in dense layers, reduces mixing and dilution, and resists vertical transport. This causes local buildup and a rise in the overall concentration of the system.