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Viscothermal Damping in Thin Gas or Fluid Layers


 This paper deals with viscothermal wave propagation, including acousto-elastic interaction. For wave propagation in thin gas or fluid layers, the effects of viscosity and thermal conductivity have to be accounted for. These effects can introduce a significant dissipation of energy. A model to describe viscothermal wave propagation was developed. It includes the effect of inertia, viscosity, compressibility and thermal conductivity. It was written in terms of dimensionless parameters. These parameters govern the validity of simplifications and they can be used to put models into perspective. The viscothermal model is validated with specially designed experiments. A numerical finite element model was developed that includes the full acousto-elastic coupling. This model was also validated with experiments. The influence of barriers in a thin layers was investigated experimentally. Finally, the new techniques were applied to a number of practical problems: the damping of double wall panels and the dynamical behaviour of a folded array of solar panels during launch.