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Fluid Damper

Fluid dampers are used in military devices for shock isolation and in civil structures for suppressing earthquake-induced shaking and wind-induced vibrations, among many other applications. Fluid dampers work by dissipating the mechanical energy into heat. This model shows the phenomenon of viscous heating and consequent temperature increase in a fluid damper. Viscous heating is also important in microflow devices, w ...
www.comsol.com/model/8568

Voltage Induced in a Coil by a Moving Magnet

A magnet moving axially through the center of a coil will induce a voltage across the coil terminals. One practical application of this is in shaker flashlights, where the flashlight is vigorously shaken back and forth, causing a magnet to move through a multi-turn coil, which provides charge to the battery. In this model, the motion of a magnet through a coil is modeled, and the induced voltages are computed. The di ...
www.comsol.com/model/14163

Microwave Filter on PCB

Microstrip filters can be fabricated directly on a printed circuit board (PCB) with a microstrip line going from the input to the output. Along the microstrip line there are a number of stubs of certain lengths and widths. The design of the filter involves choosing the impedance of the microstrip line, the impedance of the stub microstrips, and the length of the stubs. This particular filter has a seventh-pole low ...
www.comsol.com/model/4461

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 in which it removes soo ...
www.comsol.com/model/1394

Sensitivity Analysis of a Communication Mast Detail

The example Stiffness Analysis of a Communication Mast’s Diagonal Mounting in the COMSOL Multiphysics Model Library shows how you can modify a 3D CAD model to improve its performance. In that case, the applied changes were based solely on the analyst’s experience with similar structures. A senior design engineer can sometimes reach acceptable performance after analyzing only a handful of designs, while an un ...
www.comsol.com/model/4737

Superfilling Electrodeposition

This example illustrates the concept of superfilling in electrodeposition. The deposition rate is accelerated in concave areas of the surface, where the concentration of a surface catalyst is increased due to the area contraction of the moving boundary. ...
www.comsol.com/model/12343

Thermally Induced Focal Shift

Modern high-power industrial fiber laser systems can deliver up to 3kW of single-mode laser radiation on to surfaces to be cut, drilled, welded or marked. Even using highly transmissive materials, the optical component used to focus the laser beam on to target surfaces can be affected by the large amount of power carried by the light. As the laser beam pass through the optical components, thermal expansion as well ...
www.comsol.com/model/19955

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. ...
www.comsol.com/model/12619

Electrochemical Polishing

This example illustrates the principle of electrochemical polishing. The simplified 2D model geometry consists of two electrodes and an intermediate electrolyte domain The positive electrode has a protrusion, representing a surface defect. The purpose of the model is to examine how this protrusion and the surrounding electrode material are depleted over a period of time. ...
www.comsol.com/model/979

Capacitive Pressure Sensor

A capacitive pressure sensor is simulated. This model shows how to simulate the response of the pressure sensor to an applied pressure, and also how to analyze the effects of packing induced stresses on the sensor performance. ...
www.comsol.com/model/476

Axisymmetric Condenser Microphone with Electrical 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 electrostatics and a m ...
www.comsol.com/model/10731

Freeze-Drying

uses the arbitrary Lagrangian-Eulerian (ALE) method to compute the coupled heat and mass balances on a moving mesh attached to the advancing vapor-ice interface. ...
www.comsol.com/model/3924

Stiffness Analysis of a Communication Mast's Diagonal Mounting

Communication masts usually have a framework with a bolted triangular lattice design. The diagonals of the framework are assembled from several parts and welded together. When operating under a given wind load at a specific location, the antenna’s total rotation angle should stay below a certain limit to ensure uninterrupted communications. For the type of mast in this model, the engineers have determi ...
www.comsol.com/model/1363

Copper Deposition in a Trench

This model demonstrates the use of moving meshes in the application of copper electrodeposition on circuit boards. In these environments, the presence of cavities or 'trenches' are apparent. The model makes use of the Tertiary, Nernst-Planck interface for electrodeposition to keep track of the deformation of the mesh. Furthermore, electrochemical reaction kinetics through use of the Butler-Volmer equation fo ...
www.comsol.com/model/2112

Generator in 2D

In this model, a rotor with permanent magnets and a nonlinear magnetic material rotates within a stator of the same magnetic material. The generated voltage in windings around the stator is calculated as a function of time. COMSOL Multiphysics models the rotation with assemblies and identity pairs. The nonlinearity of the magnetic material is also taken into account using an interpolation function. ...
www.comsol.com/model/2122

Fluid-Structure Interaction in a Network of Blood Vessels

This model refers to a portion of the vascular system of a young child - the upper part of the aorta artery. The blood vessels are embedded in a biological tissue (the cardiac muscle) and, during the flow of blood, pressure is applied to the internal surfaces producing deformation of the vessel walls. The complete analysis consists of two distinct but coupled procedures: a fluid-dynamics analysis with t ...
www.comsol.com/model/660

Peristaltic Pump

In a peristaltic pump, rotating rollers squeeze a flexible tube. As the rollers move along the tube, the fluid in the tube follows the motion. The main advantage of the peristaltic pump is that no seals, valves or other internal parts ever touch the fluid. Due to their cleanliness, peristaltic pumps have found many applications in the pharmaceutical, chemical, biomedical and food industries. This COMSOL M ...
www.comsol.com/model/985

Axisymmetric Condenser Microphone

This is a model of a condenser microphone with a simple axisymmetric geometry. The model aims to give a precise description of the physical working principles of such a microphone. The condenser microphone is considered to be the microphone with highest quality when performing precise acoustical measurements and with high-fidelity reproduction properties when performing sound recordings. This electro-mechanical acous ...
www.comsol.com/model/12377

The Brüel & Kjær 4134 Condenser Microphone

> Thermoacoustics Membrane Electrostatics Moving mesh ALE About Brüel and Kjær: Brüel & Kjær is a world leading manufacturer and supplier of sound and vibration test and measurement solutions. The products range from transducers (measurement microphones and vibration transducers), data acquisition and analysis software and hardware, hand held sound level meters ...
www.comsol.com/model/12375

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 shows how to app ...
www.comsol.com/model/4353