Highlights
Full-year monitoring of noise level in central Stockholm, including CoViD-19 period.
Impact of the virus spread and Swedish mitigation strategy on human activity.
Urban noise level reduced up to 4 dB(A) following the national recommendations.
Noise levels in the range of the two major Swedish Public holidays for over a month.
Contrary to discussions in media on the Swedish strategy, strong impact measured.
Structural-acoustic finite element models including three-dimensional (3D) modeling of porous media are generally computationally costly. While being the most commonly used predictive tool in the context of noise reduction applications, efficient solution strategies are required. In this work, an original modal reduction technique, involving real-valued modes computed from a classical eigenvalue solver is proposed to reduce the size of the problem associated with the porous media. In the form presented in this contribution, the method is suited for homogeneous porous layers. It is validated on a 1D poro-acoustic academic problem and tested for its performance on a 3D application, using a subdomain decomposition strategy. The performance of the proposed method is estimated in terms of degrees of freedom downsizing, computational time enhancement, as well as matrix sparsity of the reduced system.
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