The Brüel & Kjær 4134 Condenser Microphone
This is a model of the Brüel and Kjær 4134 condenser microphone. The geometry and material parameters are those of the actual microphone. The modeled sensitivity level is compared to measurements performed on an actual microphone and shows good agreement. The membrane deformation, pressure, velocity, and electric field are also determined. The model is a true multiphysics problem that ...
Transient Gaussian Explosion
An ellipse with sound-hard walls has the interesting property that an acoustic signal emanating from one of the foci refocuses at the other focal point b/c seconds later, where b (in meters) is the major axis length and c (m/s) is the speed of sound. This model involves a Gaussian explosion at one focus of an ellipse to illustrate some properties of time-dependent acoustic problems. The ...
Vibrating Plate in a 2D Viscous Parallel Plate Flow
This is a small 2D demonstration model that couples the *Linearized Navier-Stokes, Frequency Domain*, *Solid Mechanics*, and *Creeping Flow* physics interfaces to model the vibrations of a plate located in a 2D viscous parallel plate flow. This type of model is used to model fluid-structure interaction (FSI) in the frequency domain. For simplicity, the flow is assumed to be a creeping flow. ...
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 ...
Acoustic Cloaking
Two articles in the New Journal of Physics describe how to derive necessary conditions on an anisotropic density tensor to create a perfect acoustic cloak in 2D, and show how this material can be realized in practice as a layered shell with isotropic properties in each layer. These two example files illustrate simplest possible implementations using both anisotropic density and the layered ...
Transfer Impedance of a Perforate
Perforates are plates with a distribution of small perforations or holes. They are used in muffler systems, sound absorbing panels, and in many other places as liners, where it is important to control attenuation precisely. As the perforations become smaller and smaller, viscous and thermal losses become more important. The attenuation behavior, which is also frequency dependent, can be ...
Small Concert Hall Analyzer
Designing structures and open spaces with respect to sound quality is important for concert halls, outdoor environments, as well as the rooms of a house. You can simulate acoustics in the high-frequency limit, where the wavelength is smaller than the geometrical features, with ray acoustics. This application analyzes the acoustics of a small concert hall using the *Ray Acoustics* physics ...
Lumped Loudspeaker Driver
This is a model of a moving-coil loudspeaker where a lumped parameter analogy represents the behavior of the electrical and mechanical speaker components. The Thiele-Small parameters (small-signal parameters) serve as input to the lumped model, which is represented by an Electric Circuit physics. The lumped model is coupled to a 2D axisymmetric Pressure Acoustics model describing the ...
Muffler with Perforates
Reflective mufflers are best suited for the low-frequency range where only plane waves can propagate in the system, while dissipative mufflers with fibers are efficient in the mid- to high-frequency range. Dissipative mufflers based on flow losses, on the other hand, also work at low frequencies. A typical automotive exhaust system is a hybrid construction consisting of a combination of ...
Gaussian Pulse Absorption by Perfectly Matched Layers: Pressure Acoustics, Transient
This tutorial simulates a standard test and benchmark model for perfectly matched layers (PMLs) as absorbing boundary conditions in the time domain. It involves the propagation of a transient Gaussian pulse with no flow. The _Pressure Acoustics, Transient_ interface is used together with PMLs to reduce the computational domain and suppress the reflections from the artificial boundaries. An ...