Acoustic Muffler with Thermoviscous Acoustic Impedance Lumping
This model utilizes the thermoviscous acoustic interface in a sub-model to obtain detailed results for the transfer impedance of a perforated plate (including the thermal and viscous losses). The impedance is in turn used as an internal impedance in a pressure acoustic model of a muffler. The results are compared to classic impedance models and measurements.
Optimizing the Shape of a Horn
A plane-wave mode feeds an axisymmetric horn radiating from an infinite baffle towards an open half space. The radius of the feeding waveguide is assumed to be fixed, as well as the depth of the horn and the size of the hole where the horn is attached to the baffle. By varying the curvature of the initially conical surface of the horn, its directivity and impedance can be changed. This model ...
Acoustics of a Pipe System with 3D Bend and Junction
This tutorial shows how to model the propagation of acoustic waves in large pipe systems by coupling the *Pipe Acoustics* interface to the *Pressure Acoustics* interface. The tutorial is set up in both the time domain and the frequency domain. 1D pipe acoustics is used to model the propagation in the long straight pipe portions. A 3D model of a pipe junction and pipe bend is coupled to the 1D ...
Vibrating Micromirror with Viscous and Thermal Damping
Micromirrors are used in certain MEMS devices to control optic elements. This model of a vibrating micromirror surrounded by air uses the Thermoacoustic-Shell Interaction user interface to model the fluid-solid interaction, and it thus includes the correct viscous and thermal damping of the mirror from the surrounding air. The resonance frequency of the mirror when under a torquing load is ...
Radially Polarized Piezoelectric Transducer
This tutorial model shows how a user-defined coordinate system can be used to create any type of directional polarization of a piezoelectric material. Results are shown for the case of radial polarization of a piezoelectric disk. The piezoelectric material is PZT-5H. The example shows a static analysis. Visualization of the cylindrical coordinate system as well as the stress/strain in that ...
Multilayered Porous Material: Poroelastic Waves with Thermal and Viscous Losses (Biot-Allard Model)
In applications where pressure and elastic waves propagate in porous materials filled with air, both thermal and viscous losses are important. This is typically the case in insulation materials for rooms, lining materials in car cabins, or foams used in headsets and speakers. Another example is porous material in mufflers in the automotive industry. In many cases, these materials can be modeled ...
Nonlinear Acoustics — Modeling of the 1D Westervelt Equation
This model example shows how to model nonlinear propagation of 1D finite-amplitude Acoustic waves in fluids using Acoustics Module of COMSOL Multiphysics. The model is based on the 2nd order Westervelt equation. The one dimensional nonlinear wave equation is solved in the time domain by adding the nonlinear term to the linear equation. The model does not include energy dissipation in order to ...
Anechoic Coating
Anechoic coatings are used for lowering visibility to sonars, for example on submarines. This model calculates the reflection, absorption, and transmission properties of an anechoic coating on a steel plate based on a setup from literature.
Lumped Receiver Connected to Test Set-up with a 0.4cc Coupler
In this model a Knowles ED23146 receiver (miniature loudspeaker) is connected to a test set-up consisting of a 50 mm (1 mm diameter) earmold tube and a so-called 0.4-cc coupler. The receiver is modeled using a lumped spice network and connected to the finite element domain at the tube inlet. The response at the measurement microphone in the coupler as well as the electric input impedance to the ...
Acoustic-Structure Interaction and Air Flow in Violins
These models are featured in the blog post [Analyze Violin Tone and Volume with Multiphysics Modeling](http://www.comsol.com/blogs/analyze-violin-tone-and-volume-with-multiphysics-modeling/). One applies acoustic-structure interaction to study how the air mode resonance is affected by the coupled vibrations in the violin body. The other uses a potential flow approximation to find out how the air ...
