A Computational Study of Outwash Mitigation using Surface Modification on Vertipads

This paper presents a computational fluid dynamics (CFD) investigation of vertipad surface configurations for mitigation of e-VTOL rotor outwash. The outwash is modelled as a coherent vortex train embedded in a wall jet, simulated using 2D and 3D Large Eddy Simulation (LES). In 2D simulations, a tilted vane surface is shown to break up the coherent vortex train and induces recirculation beneath the vertipad, producing a sustained viscous energy dissipation rate approximately four times higher than the no-vertipad case. 3D simulations evaluate a novel fractal panel concept, comparing it against flat surface, grated panel, and no-vertipad configurations. The fractal panel produces the highest rates of vortex fragmentation and viscous energy dissipation, with sustained rates 90% higher than the no-vertipad configuration, and 30% higher than the next-best-performing grated panel. The results demonstrate that passive vertipad surface modification is an effective outwash mitigation strategy.