A new approach to aircraft ditching analysis by coupling free surface lattice Boltzmann and immersed boundary method incorporating surface tension effects

Abstract

This study primarily addresses the phenomenon of aircraft ditching. This phenomenon presentspresenting a significant challenge for numerical simulations due to its highly nonlinear and multiphase-coupled water entry impact problem involving fluid-structure interaction. Traditional numerical methods have difficulties and deficiencies in free surface evolution and accuracy. An improved iterative velocity correction scheme has been presented by coupling the single-phase free surface-lattice Boltzmann method (FS-LBM) based on the volume of fluid method with the immersed boundary (IB) method to simulate water entry impact issues. Notably, this model incorporates the effect of surface tension, enhancing its ability to accurately simulate various phenomena, such as rolling, breaking, splashing, and fusion with the free surface in gas-liquid-solid multi-physical field conditions. Through the correction of the boundary force of the interface lattice and the gas lattice and the improved scheme, the non-slip boundary is satisfied, and the particle penetration is prevented. Furthermore, several benchmark tests have been conducted to verify the rationality and feasibility of the FS-LBM-IB method in simulating aircraft ditching. A scaled model of an aircraft has been developed to investigate the dynamic response characteristics of aircraft ditching at a specific attitude angle, with the simulation results confirming the accuracy of the FS-LBM-IB method in predicting the secondary head-up of the aircraft under suction force. This research highlights the efficiency of the FS-LBM-IB method as a novel approach for simulating aircraft ditching behavior.