This study presents an exact analytical investigation of electromagnetohydrodynamic (EMHD) boundary-layer flow over an exponentially stretching surface, incorporating coupled heat and mass transfer with thermal radiation and magnetic field effects. The governing momentum, energy and concentration equations are transformed into normal coordinates and solved using a Fourier transform framework. Radiative heat flux is modeled via the Rosseland approximation, leading to a modified effective thermal diffusivity. Closed-form exponential expressions are obtained for the temperature and concentration distributions, while the velocity field is recovered through inverse Fourier transformation, accounting for thermal and solutal buoyancy coupling. The results indicate that temperature and concentration profiles exhibit exponential decay away from the surface, governed by radiation-modified Prandtl and Schmidt numbers. The applied magnetic field suppresses fluid motion, whereas thermal and solutal Grashof numbers enhance the velocity due to buoyancy effects. Increasing thermal radiation thickens the thermal boundary layer, reducing the Nusselt number and consequently the surface heat transfer rate, while higher Prandtl and Schmidt numbers significantly improve thermal and mass transport characteristics. Entropy generation analysis is performed to quantify thermodynamic irreversibility, revealing the combined influence of viscous dissipation and magnetic effects. The Bejan number distribution shows that heat transfer irreversibility dominates in the near-wall region. Furthermore, a multi-objective optimization framework is developed to simultaneously maximize heat transfer and minimize entropy production. The analysis demonstrates that optimal system performance is achieved at moderate Prandtl number, low radiation parameter and controlled magnetic field intensity. The present analytical solutions provide both physical insight and computational efficiency, offering a reliable framework for the design and optimization of advanced EMHD-based thermal-fluid systems.
Ojo et al. (Mon,) studied this question.