Acoustics DGM

Modeling noise propagation in complex flows using linearized Euler equations and discontinuous Galerkin methods Actran DGM solves the linearized Euler equations using discontinuous finite elements and is used for predicting the noise propagation in complex physical conditions. It is particularly well suited to solving aero-acoustic problems at the exhaust of a double flux aero-engine, including effects such as propagation through strong shear layers, high temperature gradients and non-homentropic mean flows. Actran DGM can address 2D, 2.5D (axisymmetric with azimuthal order) or 3D problems. It includes all required boundary conditions: decomposition of the engine excitation in duct modes, non-reflective boundary conditions with absorbing buffer zones; liners are modeled using a time-domain translation of the Myers BC (Extended Helmholtz Resonator Model). The straightforward mesh generation is one of the key advantages of Actran DGM. As an unstructured mesh method, it is not submitted to the standard constraints of a Finite Difference mesh. As the order of the elements is automatically adapted, the mesh can be “non-homogeneous” (i.e. using very small and large elements in the same model) without any performance degradation. In addition, the same mesh can be reused for frequencies of ratio 1 to 4 (i.e. a mesh that was designed to run at a frequency of 1000Hz can be used for frequencies ranging from 500Hz to 2000Hz). Thanks to the implementation of a discontinuous spatial scheme for solving the Linearized Euler Equations, the performance is highly scalable in parallel. This scalability of the RAM consumption and computational time makes the solution of very large problems (in terms of kR) possible. Model courtesy of Airbus™ Target Applications: Exhaust of turbomachines Inlet of large turbomachines All acoustic propagation problems with non-homogeneous mean flow conditions