Journal Article

Natural Convective Heat and Mass Transfer Flow in a Doubly Stratified High Porosity Medium

Sifath, Silvia, Azam Khan Muzahid, Md, Akimul Islam Saikat, Md, Hossain, Muhammad Shakhawat, Islam, Md. Mainul, Ahmed Foisal, Abdullah

2026

Overview

Natural convection heat and mass transport in porous media is a fundamental phenomenon that has many uses in material processing, energy systems, and environmental engineering. Increasing the effectiveness of heat exchangers, geothermal energy extraction, and soil moisture retention, among other processes, requires an understanding of the behavior of fluid flow in doubly stratified high porosity media. The majority of current research concentrates on stable natural convection, whereas some studies ignore how magnetic fields, double stratification, and Darcy factors affect unsteady natural convection. This study aims to develop a novel double‐stratification convection model that incorporates both thermal and mass stratification, including the Darcy number (D) and magnetic parameter (M) in a unified framework to effectively depict convection in stratified systems. In the governing boundary layer equation, the system of non‐linear coupled partial differential equations is transformed by the standard transformation into a non‐dimensional system of coupled non‐linear partial differential equations. To solve this system numerically, the explicit finite difference approach will be applied. The numerical solutions were derived using Compact Visual FORTRAN 6.6a and MATLAB R2015. To completely understand the impact of physical characteristics, a thorough analysis of the stability and convergence criteria was conducted. Graphics will be used to illustrate the doubly stratified effects on temperature, velocity, concentration, shear stress, and Nusselt number. The mesh sensitivity and validation tests have been performed and presented, while the time‐sensitivity test yields the dimensionless time. The results of this study will be analyzed for different values of the specified parameters and shown graphically. The effects of important parameters were investigated, such as the thermal stratification number (), mass stratification number (), Darcy number (D), and Prandtl number (Pr). The findings demonstrate that while concentration rises, velocity and temperature fall as the Prandtl number rises. Higher Darcy numbers also cause temperature and concentration to drop while velocity increases. Higher thermal stratification decreases local shear stress but raises the Nusselt number, based on the results of an investigation into the effects of these parameters on shear stress and Nusselt number. It performs 15% better than the previous work of Ganesan, under a specified threshold value. These results offer a deeper comprehension of the physical behavior of the model under various circumstances. These findings also provide quantitative insight into magnetohydrodynamic transport mechanisms in doubly stratified porous media relevant to geothermal energy systems, subsurface fluid transport, and filtration processes.

• Publisher: John Wiley & Sons, Inc,Wiley
• Subject: Boundary layer equations / Chemical reactions / Chemical reactors / Darcy number / Efficiency / Energy storage / Environmental engineering / Fluid flow / Free convection / Geothermal energy / Geothermal energy extraction / Heat / Heat exchangers / Investigations / isothermal / Magnetic fields / Magnetic properties / mass stratification / Mass transfer / Mass transport / natural convection / Nuclear energy / Nuclear power plants / Nusselt number / Parameters / Partial differential equations / Physical properties / Porous media / Prandtl number / Radiation / Reynolds number / Sensitivity / Shear stress / Soil moisture / Soil porosity / Stress concentration / Temperature effects / Thermal stratification / transient