Double diffusive convection in flow along heated and non-uniform cylinder with nonlinear kinematics

Abstract

This study investigates double diffusive convection in viscous fluid flow over a vertically aligned, heated, porous, and non-uniform cylinder exhibiting nonlinear stretching and shrinking. The field variables velocity, temperature, and concentration are modeled using nonlinear algebraic functions. By applying similarity transformations, the governing partial differential equations are reduced to a system of four coupled nonlinear ordinary differential equations, solved using MATLAB’s bvp4c scheme. The results show that increasing the thermal and solutal Grashof numbers by a factor of 2 leads to an increase of approximately 58% in the axial velocity near the cylinder surface, enhancing assisting flow behavior. An increase in the nonlinear stretching parameter reduces the thermal boundary layer thickness by up to 35%, while the mass transfer rate increases by over 40% in highly porous conditions. Skin friction coefficients and Nusselt and Sherwood numbers display strong nonlinear sensitivity to surface roughness and porosity. Notably, overshoot in velocity profiles is observed under specific parameter conditions, whereas temperature and concentration profiles remain monotonic. This model generalizes previous studies by encompassing both uniform and non-uniform surface properties and provides a versatile tool for simulating practical heat and mass transfer processes.