Generalized Wagner model for 2D symmetric and elastic bodies
ABSTRACT We propose an algorithm to solve the generalized Wagner problem for two dimensional symm... more ABSTRACT We propose an algorithm to solve the generalized Wagner problem for two dimensional symmetric and elastic bodies.
ABSTRACT Since the pionneering works by Wagner hydrodynamic models for impact of bodies onto a fl... more ABSTRACT Since the pionneering works by Wagner hydrodynamic models for impact of bodies onto a flat free surface have been continuously developed. First Wagner proposed a model based on the flat disk approximation under the assumption that the deadrise angle is small. However, there are many situations where the linearization of the boundary condition on the wetted surface is not valid any longer. For a standard use in industry more friendly models can be developed. As an intermediate step, Mei et al proposed a generalized Wagner model, formulating the boundary value problem (BVP) in potential theory, with no gravity and no surface tension. The originality of this technique comes from the fact that the dynamic free surface boundary condition reduces to a homogeneous Dirichlet condition for the potential on a horizontal line emanating from the contact points. On the basis of their works we consider here the impact of an asymmetric body. To this end, conformal mapping are implemented. The computational domain is bounded by the lower half space and the physical body contour is turned into a flat plate. We formulate a BVP in this domain. A method of resolution of this BVP is developed in the sequel and the mass conservation law is studied. We give some applications concerning the symmetric wedge, for which analytical solution is available. We finally draw method of solution for more complicated shapes and for the fully hydroelastic coupling as well.
Cetteétude porte sur l'interaction fluide-structure se produisant lors de l'impact hydrodynamique... more Cetteétude porte sur l'interaction fluide-structure se produisant lors de l'impact hydrodynamique d'un corps souple et gonflé sur un liquide au repos. L'objectif industriel est de mieux modéliser le comportement de systèmes de flottabilités gonflés lors de l'amerrissage d'hélicoptères. Une campagne expérimentale ainsi que des simulations numériques sont menées. Des comparaisons modèle numérique -expériences sont réalisées pour les premiers instants de pénétration.
Many situations in hydraulic engineering require the use of numerical modelling. Developments in ... more Many situations in hydraulic engineering require the use of numerical modelling. Developments in this field began about 50 years ago and the resulting computational codes have now reached maturity. A current trend (not restricted to hydraulics) consists in global modelling and building Decision Support Systems. This necessitates taking into account a large number of phenomena and often presupposes coupling appropriate computational codes. Moreover, many models have been built in recent years but this requires much time and effort since whole rivers (and sometimes their tributaries) are often under consideration. So, when undertaking a new study, the reuse of existing models considerably reduces engineering time. The possible lack of information in an existing model can be compensated for by coupling it to another model, thereby giving access to the missing information. This study investigates the available techniques for coupling hydraulic models with different spatial dimensions ). An easy-to-use framework, called PALM, is compared to the other existing tools, and adopted for further study. The way to perform coupling of existing and relatively complex code in such a framework is detailed. We focuss on the reduced invasivity of PALM, which makes it very convenient for algorithm testing and prototyping. Results on real-world hydraulic cases are shown, in order to demonstrate the performance of this approach, compared to less accurate coupling, based on file exchange for example.
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Papers by N. Malleron