Quarter wavelength resonator provides a mean to create a pressure drop at a specified frequency. Design of hollow cylinder connected radially to a pipe was used and different lengths of this tuned resonator were measured. Correlation with computational approach using finite element method analysis (FEM) with ANSYS acoustics capabilities was achieved. Analytical formula for a length of a quarter wavelength resonator is compared to an experimental measurement data and simulation.

Bulk viscosity is an important factor in the damping properties of fluid systems and exhibits frequency dependent behaviour. A comparison between modal analysis in ANSYS Acoustics, custom code and experimental data is presented in this paper. The measured system consists of closed ended water-filled steel pipes of different lengths. The influence of a pipe wall, flanges on both ends and longitudinal waves in the structural part were included in measurement evaluation. Therefore, the obtained values of sound speed and bulk viscosity are parameters of the fluid. A numerical simulation was carried out only using fluid volume in a range of bulk viscosity. Damping characteristics in this range were compared to measured values. The results show a significant influence of sound speed and subsequently, the use of sound speed value regressed from experimental data yields a better fit between the measurement and the computation.

Eigenfrequency of object drops when it is submerged in the water compared to an air exposition. In this article the effect of partial submersion on dynamic properties of steel plate is investigated. Changes differ by a type of particular modeshape because of relative position of nodes and antinodes to free surface. Dynamic properties are influenced mainly by position of antinodes, in which maximal displacement occurs. Comparison of experiment, FEM simulation in ANSYS and custom code analytical solution is presented. Added effects of fluid on the steel plate are discussed.

Abstract. Additional effect of fluid on the solid body is often ignored phenomenon. Although it is possible to do an analytic derivation of equations describing additional effects for many various conditions, it can be difficult to solve them. The paper shows pressure pulsations in the pipe with piston solved by transfer matrix and harmonic analysis with ANSYS Acoustics, where effect of second viscosity is included.

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