Fluid/structure interaction analysis using the Smoothed Particle Hydrodynamic method (original) (raw)
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Fluid/structure intercation analysis using Smooth Particle Hydrodynamic method
2010
Works presented in this paper have been performed within the GARTEUR Action Group AG15 “Improvement of SPH methods for application to helicopter ditching” whose overall objective aimed at assessing analytical tools for the simulation of helicopter impacts on water. It especially focused on the Smooth Particle Hydrodynamic (SPH) formulation which consists of a gridless Lagrangian method and whose main interest, with respect to fluid/structure interaction issues, relies upon the absence of connectivity between the “particle elements”, thus permitting to cope with large deformations without generating mesh distortion problems. In a first step, the SPH method was evaluated through the simulation of droplets impact tests onto rigid plate, performed at two impact velocities (1 m/s and 5 m/s); numerical results were analysed in terms of force and impulsion data and proved to conveniently fit with the tests results. In a second step, water impact tests on simple shapes were simulated. On th...
Simulations of helicopter ditching using smoothed particle hydrodynamics
Journal of Hydrodynamics, 2020
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Journal of Offshore Mechanics and Arctic Engineering, 2014
A numerical study on the dynamic response of a generic rigid water-landing object (WLO) during water impact is presented in this paper. The effect of this impact is often prominent in the design phase of the re-entry project to determine the maximum force for material strength determination to ensure structural and equipment integrity, human safety and comfort. The predictive capability of the explicit finite-element (FE) arbitrary Lagrangian-Eulerian (ALE) and smoothed particle hydrodynamics (SPH) methods of a state-of-the-art nonlinear dynamic finite-element code for simulation of coupled dynamic fluid structure interaction (FSI) responses of the splashdown event of a WLO were evaluated. The numerical predictions are first validated with experimental data for maximum impact accelerations and then used to supplement experimental drop tests to establish trends over a wide range of conditions including variations in vertical velocity, entry angle, and object weight. The numerical res...
International Journal of Crashworthiness, 2003
The study of hydrodynamic impact between a body in motion and a free water surface finds applications, in aeronautical fields, in splashdown and ditching problems. The effect of this impact is often prominent in the design phase of the project and, therefore, the importance of studying the event with more accuracy than in the past is imperative. Usually the study of the phenomenon is dealt with experiments, empirical laws, and lately, with finite element simulations. These simulations are performed by means of special codes that allow the fluid-structure coupling; these codes have their origin in Lagrangian finite element programs developed for crash analysis improved with possibility of interfacing with Eulerian spatial description, typical of fluids. Critical points in this type of modelling are the fluid-structure interaction algorithms, constitutive modelling of the fluid and time efficiency of the computation. This study describes an effort that focuses on the development of a crash modelling and simulation approach utilizing a non-linear explicit finite-element code (LSDYNA 960) to demonstrate the potential for helicopter water impact analysis in the development of crash design criteria and concepts. Initially, the water model shall be developed and validated using default Lagrangian techniques. Subsequently, more accurate Arbitrary Lagrangian Eulerian analyses will be conducted to obtain finer results for the ball impact scenario and helicopter impact. Finally, the response of an occupant for the above helicopter crash test shall be analyzed using the MADYMO code, utilizing accelerations obtained from the LSDYNA output. Lumbar load, the most crucial mode of injury in these types of crashes will be investigated and discussed.
Fluid-structure interaction by the mixed SPH-FE method with application to aircraft ditching
The International Journal of Multiphysics, 2015
This paper deals with numerical simulation of fluid-structure interaction as it occurs during aircraft ditching-an emergency condition where an aircraft is forced to land on water. The work is motivated by the requirement for aircraft manufactures to analyze ditching as part of the aircraft certification process requested by airworthiness authorities. The strong interaction of highly non-linear fluid flow phenomena and structural responses requires a coupled solution of this transient problem. Therefore, an approach coupling Smoothed Particle Hydrodynamics and the Finite Element method within the commercial, explicit software Virtual Performance Solutions has been pursued. In this paper, several innovative features are presented, which allow for accurate and efficient solution. Finally, exemplary numerical results are successfully compared to experimental data from a unique test campaign of guided ditching tests at quasi-full scale impact conditions. It may be concluded that through the application of state-of-the-art numerical techniques it has become possible to simulate the coupled fluidstructure interaction as occurring during ditching. Therefore, aircraft manufacturers may significantly benefit from numerical analysis for design and certification purposes.
Evaluation of a Euler/Lagrange coupling method for the ditching simulation of helicopter structures
The paper deals with the evaluation of an Euler/Lagrange coupling interface implemented in the RADIOSS code, to cope with the modelling of fluid/structure interaction. In a first step, a parametric study on the structure/fluid mesh sizes ratio and the contact gap is performed, through the simulation of a rigid flat plate impact on water. In a second step, the method is evaluated by simulating water impact tests performed at CEAT (French aeronautical test centre) on rigid flat and triangular shapes. Numerical results are confronted to experimental data and permit to conclude that such an Euler/Lagrange coupling interface constitutes a convenient solution to model fluid/structure interaction, in terms of physical phenomenon modelling, as well as simulation of high penetration inside water. In a last step, works are applied to the simulation of the ditching of a full-scale helicopter structure and confirm the relevance of the method for such a problematic. Results are additionally compared with those generated within the research GARTEUR group AG15 that addresses the same topic with the SPH (Smooth Particle Hydrodynamics) method.
Hydroelasticity in water-entry problems: Comparison between experimental and SPH results
Composite Structures, 2012
Hydroelastic impacts are of major interest in naval applications since, due to the mutual interaction between structural deformation and fluid motion, the impact-induced pressure and the impact dynamics can highly differ from a quasi-static solution. Hydroelastic effects are mostly important when the vessels are made with composite lightweight structures, due to the higher impact speed that can be reached. This work present an experimental and numerical study on the hydroelastic phenomena during the water-entry of elastic wedges. The numerical model is based on a coupled FEM and Smoothed Particle Hydrodynamics (SPH) formulation available in the commercial code Ls-Dyna. Results are compared with experiments about slamming of elastic wedges varying thickness, deadrise angle and impact velocity. Special attention is paid to the structural deformations. In particular, it is shown that more than one mode shape dominates the structural deformation in case of high hydroelastic impacts. Very high hydroelastic effects are observed, and the numerical solutions are found to be in good agreement with the measured data. The range of validity of the SPH technique to investigate hydroelastic effects during the water entry of elastic wedges is also outlined.
Water Impact and Sedimentation of Solid Bodies in a Newtonian Fluid using SPH Method
This paper studies the two dimensional simulation of water impact and sedimentation of circular and elliptic bodies in a Newtonian incompressible fluid using particle-based SPH (Smoothed Particle Hydrodynamics) method. The motion of the body is driven by the hydrodynamical forces and gravity. The present study shows the ability of SPH method in the simulation of nonlinear free surface problems as well as multi phase flow problems. The code is validated by a comparison of the simulation results with available experiments and other numerical methods for free falling of a circular cylinder into a liquid. SPH results show a good agreement with the experimental data and previous numerical methods. The body's path, translational velocity and rotation angle at Froude numbers of 2, 5, 8 and specific gravities of 0.25, 0.5, 0.75, 1, 1.75 and 2 are studied in detail.
International Journal for Numerical Methods in Fluids, 2009
In this study, the whole process of liquid droplet impact onto a liquid surface up to the consequent formation of the central column was simulated using the smoothed particle hydrodynamics method (SPH), and compared with an experiment using a high-speed video camera. The surface tension tensor for the particle-based expression was adequately included as the gradient of the surface tension and that enabled the simulation leading to the formations of crater and crown as well as the consequent central column. The simulated time series of the crater depth and diameter and crown height corresponded quantitatively well with the experimental result up to the rebound motion while discrepancies remained as a lower central column height in the simulation, and this seemed to be ascribed to the difficulty in realizing the complex surface structure that inevitably appeared in the fast rebound motion.