<p>The solidification of cold-core steel ingots is strongly affected by thermal compensation, melt convection, and feeding-channel connectivity. In this study, a coupled magneto-thermal-fluid model and casting experiments were used to quantify the effect of riser electromagnetic heating on melt transport and shrinkage behavior. A 1200 Hz alternating electromagnetic field was applied to the riser, with simulated powers of 10 to 50 kW and an experimental heating duration of 20 minutes after pouring. The model was validated using magnetic-flux-density measurements and thermocouple temperature histories. As the electromagnetic power increased from 10 to 50 kW, the surface magnetic flux density rose from 1.8 to 8.6 mT, while the Lorentz force density increased from 394 to 4531 N·m⁻³. The melt flow changed from an almost stagnant natural-convection state, with a maximum velocity of approximately 3 × 10⁻⁶ m·s⁻¹, to a forced-convection regime with a maximum velocity of 2.15 × 10⁻² m·s⁻¹ at 50 kW. Enhanced convection broadened the high-temperature region above 1450&#xa0;°C from 57.98 to 69.29 mm and expanded the liquid-dominant region from 30.41 to 38.89 mm. Experimental macrostructures showed that 20 kW preserved cold-core integrity, promoted metallurgical bonding, and confined shrinkage to the peripheral region, whereas excessive powers of 30 to 40 kW caused cold-core remelting and shifted shrinkage toward the centerline. These results demonstrate that the interplay between Lorentz-force-driven flow and Joule-heating-induced thermal homogenization governs melt transport and feeding behavior under electromagnetic excitation, thereby providing a mechanistic basis for optimizing electromagnetic feeding strategies in large-scale steel casting.</p>