An overall iterative method for fluid–structure interaction analysis of high-speed maglev train-guideway systems

As the operating speed of high-speed maglev trains increases, the two-way interaction between unsteady aerodynamic loads and vehicle motion becomes increasingly important. An overall iterative coupling framework integrating computational fluid dynamics (CFD) and multibody dynamics is developed to investigate the vertical fluid–structure interaction of a high-speed maglev train-guideway system. In each overall iteration, the unsteady aerodynamic load histories obtained from the flow-field simulation are applied to the train-guideway dynamic model, and the resulting vertical and pitching motions are subsequently prescribed in the CFD model to update the surrounding flow field and aerodynamic loads. For a three-car train operating at 430 km/h, the responses converge after three overall iterations. At 500 km/h, the middle car satisfies the residual criterion after three iterations, whereas the head and tail cars require a fourth iteration; the final global residuals of all response quantities are below 0.04. At 600 km/h, the self-excited lift and pitching moment increase progressively and the vehicle responses fail to converge within five overall iterations, indicating negative-aerodynamic-damping-type feedback. The 500 km/h case therefore represents a transitional but still stable coupled state between the rapidly convergent 430 km/h response and the non-convergent amplification at 600 km/h. The results demonstrate that vehicle-motion feedback modifies the integrated unsteady aerodynamic loads and coupled responses; neglecting this feedback may lead to an incomplete assessment of coupled aerodynamic and dynamic behavior.