# Model Gallery

The Model Gallery features COMSOL Multiphysics model files from a wide variety of application areas including the electrical, mechanical, fluid, and chemical disciplines. You can download ready-to-use models and step-by-step instructions for building the model, and use these as a starting point for your own modeling work. Use the Quick Search to find models relevant to your area of expertise, and login or create a COMSOL Access account that is associated with a valid COMSOL license to download the model files.

### Parameterized Busbar Geometry

This is a template MPH-file containing the physics interfaces and the parameterized geometry for the model Electrical Heating in a Busbar.

### Effective Diffusivity in Porous Materials

Transport through porous structures is usually treated using simplified homogeneous models with effective transport properties. This is in most cases a necessity, since the typical dimensions of the pores and particles making up the porous structure are several orders of magnitude smaller than the size of the domain that is to be modeled. This model introduces the concept of effective ...

### Implementing a Point Source using Poisson's Equation

This model solves the Poisson equation on a unit disk with a point source in the origin. The easiest way to describe a point source in COMSOL Multiphysics is by using an extra weak term. To obtain the weak formulation of the general Poisson equation, we multiply it with a test function u_test and integrate over the domain. The mesh density is dense, close to the origin, so as to resolve the ...

### Rock Fracture Flow

A potential flow model of fluid flow in a rock fracture uses the so-called Reynolds equation. It shows how to use experimental data interpolated to a function used in the equation.

### Acoustics of a Muffler

This is a model of the pressure wave propagation in a muffler for a combustion engine. The approach is general for analysis of damping of propagation of harmonic pressure waves. The model shows how 3D acoustics can be modeled in fairly complex geometries. It also shows COMSOL Multiphysics' coupling variable feature between different boundaries. The problem is solved in the frequency domain and ...

### Electric Sensor

This is a model from electric impedance tomography, a method of imaging the interior permittivity distribution of a body by measuring current and voltage at the surface. This model demonstrates how the shape and placement of figures with different material properties inside a closed box can be determined with this non-invasive technique. Applying a potential difference on the boundaries of ...

### Diffraction Patterns

This example resembles the well-known 2-slit interference experiment often demonstrated in schools with water waves or sound. This model mimics the plane-wave excitation with two thin waveguides leading to slits in a screen, and it computes the diffraction pattern on the screen’s other side. This diffraction pattern is clearly visible. The main effect of quantization is that the numerical ...

### Flow Between Parallel Plates

This example models the developing flow between two parallel plates. The purpose is to study the inlet effects in laminar flow at fairly moderate Reynolds numbers, in this case around 40. The problem might seem of academical nature but it is actually fairly common in catalytic reactors, heat exchangers, micro reactors etc. Symmetry along the thickness of the domain helps to reduce the ...

### Eigenmodes of a Room

When designing a concert hall it’s extremely important to take the resonances into account. For a clear and neutral sound, the eigenfrequencies should be evenly spread through the registers. For the home stereo owner, who can’t actually change the shape of his living room, another question is more relevant: where should the speakers be put for best sound? To illustrate the effects we are ...

### Joule Heating in a MEMS Device

This model exemplifies the use of the Material Library in the modeling of Joule heating in MEMS devices. The purpose of this analysis is to estimate the temperature of a conductor given an applied electrical potential difference. Both the thermal and electrical conductivities are temperature dependent. The influence of the temperature on the electrical conductivity results in a nonlinear ...