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Acoustics Including Fluid-Structure Interaction

Computational acoustics is mostly limited to a linear problem and, as such, well suited for model reduction. For example, in a modern passenger vehicle or a commercial airplane, the noise, vibration and harshness (NVH) performance is one of the key parameters, which the customer uses to assess product quality. To this end, acoustics simulation is indispensable to evaluate the low frequency NVH behavior of automotive/aircraft interiors during the design phase.

R. S. Puri, D. Morrey, A. Bell, J. F Durodola, E. B. Rudnyi and J. G. Korvink.
Compact structural-acoustic coupled models via model order reduction.
ICSV13, Thirteenth International Congress on Sound and Vibration (ICSV13), July 2 to 6, 2006, Vienna, Austria.

A reduced order model is developed for low frequency, fully coupled, undamped structural acoustic analysis of interior cavities, backed by flexible structural systems. The reduced order model is obtained by applying a projection of the coupled system matrices, from a higher dimensional subspace to a lower dimensional subspace, whilst preserving some essential properties of the coupled system. The basis vectors for projection are computed efficiently using the block Arnoldi algorithm, which generates an orthogonal basis for the Krylov subspace. Two computational test cases are analyzed, and the computational gains and the accuracy compared with the direct method in ANSYS. It is shown that reduced order model results in a very significant reduction in simulation time, while maintaining the desired accuracy of the state variables under investigation. The method could prove as a valuable tool in the analysis of complex coupled structural acoustic systems, and their subsequent optimization or sensitivity analysis, where, in addition to fast analysis, a fine frequency resolution is often required.

S. Puri, D. Morrey, A. Bell, J. Durodola, E. B. Rudnyi, J. G. Korvink.
Two-way Coupled Structural Acoustic Optimization via Model Order Reduction.
ISMA2006, International Conference on Noise and Vibration Engineering, Leuven, Belgium, September 18-20, 2006.

A reduced order model is developed for low frequency, fully coupled, undamped and constantly damped structural acoustic analysis of interior cavities, backed by flexible structural systems. The reduced order model is obtained by applying a Galerkin projection of the coupled system matrices, from a higher dimensional subspace to a lower dimensional subspace, whilst preserving some essential properties of the coupled system. The basis vectors for projection are computed efficiently using the Arnoldi algorithm, which generates an orthogonal basis for the Krylov subspace containing moments of the original system. A computational test case is analyzed, and the computational gains and the accuracy compared with the direct method in ANSYS. Further, the reduced order modelling technique is applied to a two-way coupled vibro-acoustic optimization problem, with stacking sequences of the composite structure as design variables. The optimization is performed via a hybrid search strategy combining outputs from Latin Hypercube Sampling (LHS) and Mesh Adaptive Direct Search (MADS) algorithm. It is shown that reduced order modelling technique results in a very significant reduction in simulation time, while maintaining the desired accuracy of the optimization variables under investigation.

R. S. Puri, D. Morrey, A. Bell, J. F Durodola, E. B. Rudnyi and J. G. Korvink.
Krylov Subspace Techniques for Low Frequency Structural Acoustic Analysis and Optimization.
Inter-Noise, Proceedings of the INTER-NOISE 2006, Honolulu, Hawaii, USA, 3-6 December 2006.

R. S. Puri, D. Morrey, J. L. Cipolla.
A comparison between one-sided and two-sided Arnoldi based Model Order Reduction (MORe) techniques for fully coupled Structural-Acoustic analysis.
153RD MEETING OF THE ACOUSTICAL SOCIETY OF AMERICA 4-8 June 2007, Salt Lake City, Utah, USA.
Abstract.

R. S. Puri, D. Morrey, J. F Durodola, R. C. Morgans, C. Q. Howard.
A comparison of structural-acoustic coupled reduced order models (ROMs): modal coupling and implicit moment matching via Arnoldi.
ICSV14, 14th International Congress on Sound and Vibration, Cairns, Australia, 9-12 July 2007.

R. S. Puri.
Krylov Subspace Based Direct Projection Techniques for Low Frequency, Fully Coupled, Structural Acoustic Analysis and Optimization.
PhD Thesis, 2008, Oxford Brookes University.

Contact Srinivasan Puri.