Research on cavitation vortex structures and load characteristics on of bionic manta-ray vehicles with different crossflow intensity during successive water-exit

This study numerically investigates the cavitation vortex structures and load characteristics of bionic manta ray vehicles during successive water-exit under varying crossflow intensities using the Improved Delayed Detached Eddy Simulation method, Volume of Fluid model, Schnerr-Sauer cavitation model, and overset grid technique. Understanding these mechanisms is crucial for attitude stability in adverse sea conditions. Validations based on an axisymmetric body show that the prediction errors are within the reasonable range for engineering applications, which verifies the reliability of the numerical solver. Results show that crossflow symmetry governs wake vortex evolution: without crossflow, symmetric hairpin vortices and vortex rings dominate. At dimensionless crossflow intensity U = 0.100, windward boundary-layer separation intensifies, causing twisting, stretching and skewing of vortices, leading to a strongly asymmetric three-dimensional vortex topology. Crossflow also weakens vertical deceleration. At dimensionless crossflow intensity U = 0.00, vertical velocity decays fastest with a sharp force spike. Increasing crossflow accelerates cavity collapse, reduces vertical decay rate, and lowers the impact load amplitude. High crossflow induces large periodic yaw angular velocity fluctuations, while low crossflow keeps yaw angular velocity near zero. The yaw fluctuation grows nonlinearly with crossflow intensity, posing a significant risk to attitude stability. These findings provide theoretical guidance for control and vortex management of biomimetic vehicles during trans-media water-exit.