ASSESSMENT OF COUPLED LAGRANGIAN–EULERIAN FINITE ELEMENT SIMULATIONS TO MODEL SUCTION FORCES DURING HYDRODYNAMIC IMPACTS

Abstract

During the emergency landing of an aircraft on water, the structure may experience critical forces and could eventually fail. The appropriate design of the structure should minimize the risk of occupant injuries. The recent progress in computation capabilities led to the increased use of numerical simulations in the certification process of aircraft. A specific challenge concerns the modelisation of suction forces that develop near the aircraft tail, where the first contact with water occurs. This phenomenon is due to the high horizontal velocity of the structure at impact and the longitudinal curvature of the fuselage. It can affect the overall aircraft kinematics during ditching. In this work, as an effort to improve aircraft ditching simulations and to assess the capabilities of numerical models to describe suction forces, the simple test case of the wedge water entry and subsequent exit is considered. Numerical simulations with the Eulerian formulation for the fluid and the Lagrangian formulation for the structure are used. The method used for the fluid–structure interaction is based on an immersed contact interface with penalty forces. The present work focuses on impact and suction forces modelling. Results show a satisfying capacity of the numerical approach to model negative hydrodynamic force (suction).