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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Thermionic Emission in a Planar Diode

When electrons are emitted from a heated cathode in a plane parallel vacuum diode, they contribute to the space charge density in the diode, which in turn affects the electric potential distribution. If the potential difference between the cathode and the anode is not sufficiently large, a potential minimum forms between them, repelling electrons of insufficient energy back toward the cathode. ...

Thick Plate Stress Analysis

A benchmark model where a thick plate exposed to pressure on the top surface is analyzed. The solution is compared with a NAFEMS benchmark solution.

Absorptive Muffler with Shells

This model describes the pressure wave propagation in a muffler for an internal combustion engine. The purpose of the model is to show how to analyze both inductive and resistive damping in pressure acoustics as well as coupling the fluid to the surrounding elastic shell structure of the muffler. Finally, the eigenmodes of a pure structural problem is analyzed and the modes compared to peaks ...

MOSFET with Mobility Models

This model shows how to add several linked mobility models to the simple MOSFET example.

Electromagnetic Force Calculation Using Virtual Work and Maxwell Stress Tensor

The model compare the electromagnetic force calculated by *virtual work* and *maxwell stress tensor* methods on the axial magntic bearing. The forces is evaluated by studying the effect of a small displacement on the electromagnetic energy of the system. This is done by using the *Magnetic Fields*, *Deformed Geometry* and *Sensitivity* physics interfaces.

Time-to-Frequency Fast Fourier Transform of a Coaxial Low-Pass Filter

A very wide band coaxial low-pass filter is designed using a 2D axisymmetric model. To address the wide band frequency response with a fine frequency resolution, the model is built with a transient physics interface first. Then, S-parameters are calculated using a time-to-frequency Fourier transform. To achieve a low-pass frequency response, an air-filled coaxial cable is tuned with five ...

Designing a Waveguide Diplexer for the 5G Mobile Network

A diplexer is a device that combines or splits signals into two different frequency bands, widely used in mobile communication systems. This model simulates splitting properties using a simplified 2D geometry. The computed S-parameters and electric fields at the lower and upper bands will show the diplexer characteristics in the Ka-band.

Transmission Line Butler Matrix Beamforming Network

A Butler matrix is a passive beamforming feed network. It is a cost-effective feed network for phased array antennas because the circuit can be fabricated in the form of microstrip lines and is a viable solution for performing beam scanning without deploying expensive active devices. This example shows how to design such a circuit using the *Transmission Line* interface. The results show the ...

Homogenization in a Chemical Reactor

This model illustrates how to simulate a periodic homogenization process in a space dependent chemical reactor model. This homogenization removes concentration gradients in the reactor at a set time interval. The model demonstrates a technique by which you can first stop the time-dependent solver, then restart it with an initial value obtained based on the solution.

MEMS Pressure Sensor Drift Due to Hygroscopic Swelling

For their integration in microelectronic circuits, MEMS devices are bonded on printed circuit boards and connected with other devices. Then, the whole circuit is often covered with an epoxy mold compound (EMC) to protect the devices and their interconnects with the board. The epoxy polymers used for such applications are subject to moisture absorption and hygroscopic swelling, which can lead to ...