Fluid-Structure Interaction for Hydrodynamic Problems: Impact Between a Tanker Bow Flare and a Submarine

Author(s):  
N. Aquelet ◽  
H. Lesourne ◽  
M. Souli

A methodology to predict the capacity of a nuclear submarine hull to act as a protective container and energy absorber under impact by an another underwater structure is needed. Principia Marine, company of Research in Shipbuilding (formerly IRCN, Institut de Recherche en Construction Navale), is responding to this need by developing an underwater impact crash prediction methodology based upon LS-DYNA3D software. Several physical phenomena with their own characteristic times follow one another at the time of the shock. So different but complementary tasks to develop this methodology were worked individually. This paper deals with contribution to this ongoing program that breaks up into two objectives. The first goal aims to highlight the effect of water on the structural deformation at the time of the collision between a nuclear submarine and a tanker ram bow, which is generally plane. The two-dimensional modelling of this collision uses an Eulerian formulation for the fluid and a Lagrangian formulation for the structure. The fluid-structure interaction is treated by an Euler/Lagrange penalty coupling. This method of coupling, which makes it possible to transmit the efforts in pressure of the Eulerian grid to the Lagrangian grid and conversely, is relatively a recent algorithmic development. It was successfully used in many scientific and industrial applications: the modelling of the attack of birds on the fuselage of a Jet for the Boeing Corporation, the underwater explosion shaking the oil platforms, and airbag simulation… The requirements of modelling for this algorithm are increasingly pointed. Thus, the second objective of this paper is to compare the results in pressures and velocities near the bulb for two cases, in the first one, the bulb is modelled by a slip boundary condition, in the second one, the bulb is a rigid Lagrangian structure, which involves the use of the Euler/Lagrange penalty coupling.

Author(s):  
N. Aquelet ◽  
M. Souli

During a high velocity impact of a structure on an incompressible fluid, impulse loads with high pressure peaks occur. This physical phenomenon called ‘slamming’ is a concern in the shipbuilding industry because of the possibility of hull damage. Shipbuilding companies are carrying out several studies on the slamming modeling using FEM software. This paper presents the prediction of the local high pressure load on a wedge striking a free surface. The fluid-structure interaction is simulated by a fluid-structure coupling algorithm. This method of coupling, which makes it possible to transmit the efforts in pressure from the Eulerian grid to the Lagrangian grid and vice versa, is a relatively recent algorithmic development. It was successfully used in many scientific and industrial applications: the modeling of the bird strike on the fuselage of a Jet for the Boeing Corporation, underwater explosion shaking the oil platforms, and airbag simulation in automotive industry... Predicting the local pressure peak on the structure requires an accurate fluid-structure interaction algorithm. Thus, some penalty coupling enhancements make the slamming modeling possible. The main improvement is a numerical damping factor which permits to smoothing of the pressure signal.


Author(s):  
N. Aquelet ◽  
M. Souli

During a high velocity impact of a structure on an incompressible fluid, impulse loads with high pressure peaks occur. This physical phenomenon called ‘slamming’ is a concern in the shipbuilding industry because of the possibility of hull damage. Shipbuilding companies are carrying out several studies on the slamming modeling using FEM software. This paper presents the prediction of the local high pressure load on a wedge striking a free surface. The fluid-structure interaction is simulated by a fluid-structure coupling algorithm. This method of coupling, which makes it possible to transmit the efforts in pressure from the Eulerian grid to the Lagrangian grid and vice versa, is a relatively recent algorithmic development. It was successfully used in many scientific and industrial applications: the modeling of the bird strike on the fuselage of a Jet for the Boeing Coporation, underwater explosion shaking the oil platforms, and airbag simulation in automotive industry... Predicting the local pressure peak on the structure requires an accurate fluid-structure interaction algorithm. Thus, some penalty coupling enhancements make the slamming modeling possible. The main improvement is a numerical damping factor which permits to smoothing of the pressure signal.


2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Martin Bušík ◽  
Martin Slavík ◽  
Ivan Cimrák

Modelling of cell flow for biomedical applications relies in many cases on the correct description of fluid-structure interaction between the cell membrane and the surrounding fluid. We analyse the coupling of the lattice-Boltzmann method for the fluid and the spring network model for the cells. We investigate the bare friction parameter of fluid-structure interaction that is mediated via dissipative coupling. Such coupling mimics the no-slip boundary condition at the interface between the fluid and object. It is an alternative method to the immersed boundary method. Here, the fluid-structure coupling is provided by forces penalising local differences between velocities of the object’s boundaries and the surrounding fluid. The method includes a phenomenological friction coefficient that determines the strength of the coupling. This work aims at determination of proper values of such friction coefficient. We derive an explicit formula for computation of this coefficient depending on the mesh density assuming a reference friction is known. We validate this formula on spherical and ellipsoidal objects. We also provide sensitivity analysis of the formula on all parameters entering the model. We conclude that such formula may be used also for objects with irregular shapes provided that the triangular mesh covering the object’s surface is in some sense uniform. Our findings are justified by two computational experiments where we simulate motion of a red blood cell in a capillary and in a shear flow. Both experiments confirm our results presented in this work.


Author(s):  
Prabu Ganesh Ravindren ◽  
Kirti Ghia ◽  
Urmila Ghia

Recent studies of the joined-wing configuration of the High Altitude Long Endurance (HALE) aircraft have been performed by analyzing the aerodynamic and structural behaviors separately. In the present work, a fluid-structure interaction (FSI) analysis is performed, where the fluid pressure on the wing, and the corresponding non-linear structural deformation, are analyzed simultaneously using a finite-element matrix which couples both fluid and structural solution vectors. An unsteady, viscous flow past the high-aspect ratio wing causes it to undergo large deflections, thus changing the domain shape at each time step. The finite element software ANSYS 11.0 is used for the structural analysis and CFX 11.0 is used for the fluid analysis. The structural mesh of the semi-monocoque joined-wing consists of finite elements to model the skin panel, ribs and spars. Appropriate mass and stress distributions are applied across the joined-wing structure [Kaloyanova et al. (2005)], which has been optimized in order to reduce global and local buckling. The fluid region is meshed with very high mesh density at the fluid-structure interface and where flow separation is predicted across the joint of the wing. The FSI module uses a sequentially-coupled finite element equation, where the main coupling matrix utilizes the direction of the normal vector defined for each pair of coincident fluid and structural element faces at the interface [ANSYS 11.0 Documentation]. The k-omega turbulence model captures the fine-scale turbulence effects in the flow. An angle of attack of 12°, at a Mach number of 0.6 [Rangarajan et al. (2003)], is used in the simulation. A 1-way FSI analysis has been performed to verify the proper transfer of loads across the fluid-structure interface. The CFX pressure results on the wing were transferred across the comparatively coarser mesh on the structural surface. A maximum deflection of 16 ft is found at the wing tip with a calculated lift coefficient of 1.35. The results have been compared with the previous study and have proven to be highly accurate. This will be taken as the first step for the 2-way simulation. The effect of a coupled 2-way FSI analysis on the HALE aircraft joined wing configuration will be shown. The structural deformation history will be presented, showing the displacement of the joined-wing, along the wing span over a period of aerodynamic loading. The fluid-structure interface meshing and the convergence at each time step, based on the quantities transferred across the interface will also be discussed.


Author(s):  
M’hamed Souli ◽  
Nicolas Capron ◽  
Uzair Khan

A new fluid structure interaction method is presented in the paper. The method is implemented in LSDYA, an explicit three-dimensional multi-physique code. The new algorithm is applied for different problems for industrial applications including airbag deployment in the automotive industry, where a uniform pressure computed empirically is applied to the airbag fabric material. The uniform pressure Airbag simulation does not lead to the right answer for out of position Airbag deployment. An ALE method using fluid mesh for the gas needs to be used to simulate an impact of dummy and the airbag during a crash test. In this paper, we develop the new ALE multi-material formulation and the fluid structure interaction algorithm that we developed in order to solve general fluid structure interaction problems including Airbag inflation using hydrodynamic equations for gas pressure. In the classical uniform pressure problems, the pressure in computed using a simple ideal gas law equation.


Author(s):  
Ali Marzban ◽  
Murthy Lakshmiraju ◽  
Nigel Richardson ◽  
Mike Henneke ◽  
Guangyu Wu ◽  
...  

In this study a one-way coupled fluid-structure interaction (FSI) between ocean waves and a simplified offshore platform deck structure was modeled. The FSI model consists of a Volume of Fluid (VOF) based hydrodynamics model, a structural model and an interface to synchronize data between these two. A Computational Fluid Dynamics (CFD) analysis was used to capture the breaking wave and impact behavior of the fluid on the structure using commercially available software STAR-CCM+. A 3D Finite Element (FE) model of the platform deck developed in ABAQUS was used to determine the deflection of the structure due to hydrodynamic loads. Nonlinear material behavior was used for all structural parts in the FE model. Transient dynamic structural analysis and CFD analysis were coupled by transferring the CFD-predicted pressure distribution to the structural part in each time step using the co-simulation capabilities of STAR-CCM+ and ABAQUS. The one-way FSI model was applied to investigate the possible physical causes of observed wave damage of an offshore platform deck during a hurricane. It was demonstrated that with proper physical conditions/configurations, the FSI model could reproduce a structural deformation comparable to field measurement and provide valuable insight for forensic analysis.


1980 ◽  
Vol 102 (1) ◽  
pp. 62-69 ◽  
Author(s):  
T. Belytschko ◽  
J. M. Kennedy ◽  
D. F. Schoeberle

A quasi-Eulerian formulation is developed for fluid-structure interaction analysis in which the fluid nodes are allowed to move independent of the material thus facilitating the treatment of problems with large structural motions. The governing equations are presented in general form and then specialized to two-dimensional plane and axisymmetric geometries. These elements have been incorporated in a general purpose transient finite element program and results are presented for two problems and compared to experimental results.


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