The Application Gallery features COMSOL Multiphysics® tutorial and demo app files pertinent to the electrical, structural, acoustics, fluid, heat, and chemical disciplines. You can use these examples as a starting point for your own simulation work by downloading the tutorial model or demo app file and its accompanying instructions.

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Acoustic Streaming in a Microchannel Cross Section

Recent advances in the fabrication of microfluidic systems require handling of live cells and other micro particles as well as mixing. All this can, for example, be achieved using acoustic radiation forces and the viscous drag from the streaming flow. Streaming: Due to the nonlinear terms in the Navier-Stokes equations, harmonic perturbation of the flow will lead to a net time-averaged flow ...

Loudspeaker Driver in a Vented Enclosure

This model of a boxed loudspeaker lets you apply a nominal driving voltage and extract the resulting sound pressure level in the outside room as a function of the frequency. The sensitivity, both on-axis and spatial, is determined as function of frequency. These are some of the most important design parameters for a loudspeaker. The electromagnetic properties of the driver are supplied from the ...

Cylindrical Subwoofer

In this model, the acoustic field inside and outside a down-firing subwoofer is computed. This model is set up in 2D axisymmetry using the Pressure Acoustics application mode. The modeled physical domain is a hemisphere with a radius of 1 m. To minimize the effect of non-physical reflections at the exterior boundary of this domain, an absorbing Perfectly Matched Layer (PML) is added. The ...

Acoustic-Structure Interaction with a Perfectly Matched Layer (PML)

This small tutorial model shows how to set up a model with a solid mechanics and a pressure acoustics domain including a common perfectly matched layer (PML). The PML is used to model an open or infinite domain for both the elastic waves and the pressure waves. Two configurations of PMLs exist (this model describes the first case which is also the most difficult to handle): 1. One PML should ...

Piezoelectric Tonpilz Transducer

The tonpilz (sound mushroom) piezoelectric transducer is a transducer for relatively low frequency, high power sound emission. The transducer consists of piezoceramic rings stacked between massive ends and pre-stressed by a central bolt. The tail and head mass lower the resonance frequency of the device. In this model the frequency response of the transducer when the bolt is not pre-stressed ...

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 ...

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 ...

Hollow Cylinder

Fluid acoustics coupled to structural objects, such as membranes or plates, represents an important application area in many engineering fields. Some examples are: * Loudspeakers * Acoustic sensors * Nondestructive impedance testing * Medical ultrasound diagnostics This model provides a general demonstration of an acoustic fluid phenomenon in 3D coupled to a solid object. In this study, the ...

Helmholtz Resonator with Flow: Interaction of Flow and Acoustics

Helmholtz resonators are used in exhaust systems, as they can attenuate a specific narrow frequency band. The presence of a flow in the system alters the acoustic properties of the resonator and the transmission loss of the subsystem. In this tutorial model, a Helmholtz resonator is located as a side branch to a main duct. The transmission loss through the main duct is investigated when a flow ...

Open Pipe

In this model, sound created by a vibrating piston radiates through a baffled pipe. The impedance is measured and then used in an impedance boundary condition that replaces the surrounding air domain. This technique can be employed to reduce solution time and memory usage for large models with pipe openings.