# 案例集锦

COMSOL Multiphysics 案例库模型来自广泛的应用领域，包括电气、机械、流体和化工等行业。您可以下载现成即可使用的模型，以及详细的建模步骤说明，作为您建模工作的起点。请使用“快速搜索”查找与您的专业领域相关的模型，并登录或创建一个与有效的 COMSOL 许可证相关联的 COMSOL Access 帐户，下载模型文件。

### 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 ...

### Acoustic Scattering Off an Ellipsoid

This is a tutorial model that illustrates the use of the scattered field formulation in acoustics. A solid object (here an ellipsoid) is hit by an incident plane wave field (background pressure field). The model solves for the scattered field. The model uses a PML and a far-field calculation is also added. The mesh is set up to enhance the PML and the far-field performance. ...

### Radially Polarized Spherical Piezoelectric Acoustic Transducer

This tutorial provides a step-by-step instruction to setup a fully-coupled 3D structural-acoustic interaction problem. Interaction between a vibrating spherical piezoelectric structure with the surrounding fluid media is considered. The piezoelectric material PZT-5H from the materials library is used. Instructions on how to create a radially polarized piezoelectric material in spherical ...

### 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 ...

### 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 surrounding ...

### Vibrations of a Disk Backed by an Air-Filled Cylinder

The vibration modes of a thin or thick circular disc are well known, and it is possible to compute the corresponding eigenfrequencies to arbitrary precision from a series solution. The same is true for the acoustic modes of an air-filled cylinder with perfectly rigid walls. A more interesting question to ask is: What happens if the cylinder is sealed in one end not by a rigid wall but by a thin ...

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 system ...

### Acoustic Levitator

An ultrasonic standing wave levitator, also called acoustic levitator, is a device used for levitating fluid and solid particles in an acoustic field. The standing acoustic waves exert an acoustic radiation force on the particles. The force is a second order effect and stems from a combination of the time averaged pressure and inertial interaction between the particles and the acoustic field. By ...

### Condenser Microphone, Axisymmetric with Electric Lumping

This model is that of a simple axisymmetric condenser microphone. The model includes all the relevant physics and determines the sensitivity of the specific microphone geometry and material parameters. The model uses a lumped approximation for the electric small signal problem but solves a full FE model for the acoustic-mechanical system. The quiescent (zero point) problem is solved fully using ...

### Organ Pipe Design

This tutorial model uses the Pipe Acoustics, Frequency Domain user interface to model an organ pipe. The quarter wave resonance frequency is studied with respect to dependency on the pipe radius and the pipe wall thickness. The acoustic properties of the system can easily be studied with respect to other parameters like the pipe cross section shape, the pipe material, or even a steady flow of air ...