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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Doppler Shift

We have all noticed the Doppler effect when an ambulance passes by with its sirens blaring. The siren’s pitch suddenly drops the moment the ambulance starts moving away from you. Another effect you can notice is how the siren’s sound is very loud when nearby, but as soon as the ambulance has passed the sound becomes much quieter. This model simulates the acoustic Doppler effect by placing ...

GEC CCP Reactor, Argon Chemistry, 1D

The NIST GEC CCP reactor provides a platform for studying capacitively coupled plasmas. Even the simplest plasma models are quite involved so a 1D example helps in understanding the physics without excessive CPU time. The problem has no steady-state solution, although a periodic steady-state solution is reached after a suitable number of RF cycles (usually >1000).

Thermal Bridges in Building Construction - 2D Composite Structure

This example studies heat transfer in a composite two-dimensional structure. Four materials with distinct thermal conductivities k compose the structure. The top and bottom boundaries are facing environments respectively at 0°C and 20°C. The temperature distribution and the heat flux through the structure are compared with published data. This example corresponds to the case 2 described in ...

Small Signal Analysis of a MOSFET

This model shows how to compute the AC characteristics of a MOSFET. Both the output conductance and the transconductance are computed as a function of the drain current.

Eigenfrequency Shifts Caused by Temperature Changes

This example explores the shift in natural frequencies caused by changing the temperature. One study investigates a doubly clamped beam where both ends are fixed, while the other study looks at a cantilever beam where only one end is fixed. The following effects are studied: * Stress stiffening * Change in size * Constraint effects * Temperature-dependent Young's modulus Results show that the ...

Vibrating Micromirror with Viscous and Thermal Damping: Transient Behavior

Micromirrors are used in certain MEMS devices to control optic elements. This example model illustrates a mirror that is initially actuated for a short time and then exhibits damped vibrations. It simulates a vibrating micromirror surrounded by air and uses the *Thermoviscous Acoustics, Transient*, the *Shell*, and the *Pressure Acoustics, Transient* interfaces to model the fluid-solid ...

Chemical Reactions and Soot Build-Up in a Diesel Filter

In this tutorial, a filter system for a diesel engine is modeled, including where a soot layer builds up and is oxidized. The build-up of the layer is held in check by both catalytic and non-catalytic reactions, where carbon is oxidized to carbon monoxide and carbon dioxide, which in turn passes through the membrane. A filter system's efficiency and durability is closely related to the manner ...

Edge Effects In a Spirally Wound Lithium-Ion Battery

Due to the large differences in length scales in a lithium-ion battery, with the thickness of the different layers typically being several orders of magnitude smaller than the extension in the sheet direction, a lithium-ion battery is often well represented by a one-dimensional model. However, the packing and stacking of the battery may cause edge effects which motivate modeling in higher ...

Thermal Bridges in Building Construction - 3D Structure Between Two Floors

This model studies the heat conduction in a building structure separating two floors from the external environment. Four materials with distinct thermal conductivities k compose the structure. The exterior and interior boundaries are facing environments respectively at 0°C and 20°C. The lowest temperatures on internal surfaces and the heat fluxes through each surface is compared with published ...

Tunable Evanescent Mode Cavity Filter Using a Piezo Actuator

An evanescent mode cavity filter can be realized by adding a structure inside of the cavity. This structure changes the resonant frequency lower than the dominant mode of the unfilled cavity. A piezo actuator is used to control the size of a small air gap which provides the tunability of the resonant frequency.