Heat generation–driven thermal transport in radial casson fluid flow over a stretching surface

This study numerically investigates mixed convection of a Casson fluid over a radially stretching vertical surface under heat generation/absorption, magnetic field, thermal radiation, and Soret-Dufour effects. The governing boundary-layer equations are transformed via similarity variables and solved using the Runge-Kutta-Fehlberg method with the shooting technique (RK45). Quantitative findings include: (i) switching from heat generation (ε=+0.5) to absorption (ε=-0.5) increases Nusselt number by 43.7% under default parameters; (ii) Sherwood number increases by 217.4% at high Soret number (Sr = 0.5) when switching to heat absorption; (iii) reverse mass transfer (negative Sherwood number) occurs for Sr > 0.3 under heat absorption; (iv) Dufour number reduces Nusselt number by 33% under heat generation. The Casson yield stress affects mass transfer four times more sensitively than heat transfer. A sensitivity table and convergence analysis are provided. Results are validated against published data for limiting cases of magnetic parameter and Nusselt number. Clinical trial number Not applicable.