# Application Gallery

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.

Search for tutorials and apps relevant to your area of expertise via the Quick Search feature. To download the MPH-files, log in or create a COMSOL Access account that is associated with a valid COMSOL license. Note that many of the examples featured here can also be accessed via the Application Libraries that are built into the COMSOL Multiphysics® software and available from the File menu.

### Thin Low Permittivity Gap Comparison

The thin low permittivity gap boundary condition is meant to approximate a thin layer of material with low relative permittivity compared to its surroundings. This boundary condition is available for electrostatic field modeling. This example compares the thin low permittivity gap boundary condition to a full-fidelity model and discusses the range of applicability of this boundary condition.

### Signal Integrity and TDR Analysis of Adjacent Microstrip Lines

A signal integrity (SI) analysis gives an overview of the quality of an electrical signal transmitted through electrical circuits, such as high-speed interconnects, cables, and printed circuit boards. The quality of the received signal can be distorted by noise from outside the circuit, and can be degraded by impedance mismatch, insertion loss, and crosstalk. For this reason, EMC/EMI analyses ...

### Applying a Current-Voltage Switch to Models

This example exemplifies how to model the switching between current and voltage excitations in *Terminal* boundary conditions. A more detailed description of the phenomenon and the modeling process can be seen in the blog post "[Control Current and Voltage Sources with the AC/DC Module](https://www.comsol.com/blogs/control-current-and-voltage-sources-with-the-acdc-module/)".

### Aquifer Characterization

This model uses the Optimization interface to solve the inverse problem for determining the spatially variable hydraulic conductivity on a discretized quadratic grid from a number of aquifer pump tests. Because the number of observations is smaller than the number of unknown parameters, a geostatistical penalty term is used to discriminate between solutions with comparable fitness values. ...

### Galvanic Corrosion of a Magnesium Alloy in Contact with Steel

Magnesium alloys are attractive alternatives as lightweight materials in various fields of engineering. Magnesium is however relatively non-noble and may suffer considerable galvanic corrosion when being used in conjunction with other metals, for instance when mounting an Mg alloy component using steel fasteners. This model example simulates a galvanic corrosion couple consisting of a magnesium ...

### Ultrahigh Vacuum, Chemical Vapor Deposition

Chemical vapor deposition (CVD) is a process often used in the semiconductor industry to grow layers of high-purity solid material on top of a wafer substrate. CVD is achieved using many different techniques and across a range of pressures from atmospheric to ultrahigh vacuum (UHV/CVD). UHV/CVD is performed at pressures below 10-6 Pa (10-8 Torr), so gas transport is achieved by molecular flow ...

### Equivalent Properties of Periodic Microstructures

Periodic microstructures are frequently found in composite materials, such as carbon fibers and honeycomb structures. They can be represented by a unit cell repeated along three directions of propagation. To reduce computational costs, simulations may replace all of the microscopic details of a composite material with a homogeneous domain with equivalent properties. This app computes the ...

### Superlattice Band Gap Tool

The Superlattice Band Gap Tool helps the design of periodic structures made of two alternating semiconductor materials (superlattices). The tool uses the effective mass Schrödinger equation to estimate the electron and hole ground state energy levels in a given superlattice structure. Device engineers can use the tool to quickly compute the effective band gap for a given periodic structure and ...

### Stress Relaxation of a Viscoelastic Tube

This model studies the temperature effects on the viscoelastic stress relaxation in a long thick-walled cylinder. In particular, decay of the stresses under the influence of the temperature field during a period of two hours is studied. A four-term generalized Maxwell model represents the material.

### Simulating the Motion of a Bicycle on a Flat Surface

This model demonstrates the motion of a bicycle with a hands-free rider when given an initial forward velocity and perturbed with a lean about the forward axis. This is implemented through the Multibody Dynamics module in COMSOL. The wheels of the bicycle have been modelled assuming knife-edge contact with the ground and pure rolling constraints have been implemented. Stability analysis was ...

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