Ahlem Alia

Numerical simulation of fluid structure interaction, application to vibroacoustic problems

In the present work, the transient response of a mechanical system is computed first by using an explicit finite element method. By applying the FFT, it’s transformed into frequency response which allows to use BEM for computing the noise radiated at any point into space. BEM is checked first for an acoustic problem before using it for a vibroacoustic application. The numerical examples show the efficiency of the present method.

A delayed remap technique in multi-material ALE methods

A new mesh refinement method for multi-material ALE formulations is presented. The computational timestep of this approach is divided in 2 steps: a so-called Lagrangian step, during which the mesh deforms with the update of the solution, and a so-called Eulerian step, during which the mesh is remapped in order to preserve the mesh regularity and refine in the vicinity of the shock front. As test case the method is applied to the propagation of an explosive airblast, for which experimental results are available.

Simulation of Acoustical Response Using Rayleigh Method

The Boundary Element Method is one of the most used techniques for the simulation of acoustic problems especially for external ones. However, it leads to large computational time because of the complex character of the resulting linear system and the calculation of its different terms by surface integration. In this paper, the Rayleigh method is used to calculate the acoustical pressure at any point in the space. This method is very fast since it does not need to construct and to solve a linear system.Copyright

BEM Modeling of Non Linear Systems Noise

A noticeable part of acoustic environment is made of sounds radiated by vibrating structures. Most of these sounds are considered as undesirable noise. Especially, those radiated from complex processes involving several non linear effects. In the present work, the transient response of mechanical system is computed first by using LSDYNA, an explicit finite element code for general fluid, structure and fluid-structure interaction problems. By applying the FFT, it’s transformed into frequency response which allows to use BEM for computing the noise radiated at any point into space. Results are checked for simple acoustic and classical vibroacoustic problems before applying it for a non linear case. The numerical examples show the efficiency of the present method.Copyright