# Application Gallery

The Application Gallery features COMSOL Multiphysics tutorial and demo app files pertinent to the electrical, mechanical, fluid, and chemical disciplines. You can download ready-to-use tutorial models and demo apps with step-by-step instructions for how to create them yourself. The examples in the gallery serve as a great starting point for your own simulation work.
Use the Quick Search to find tutorials and apps relevant to your area of expertise. Log in or create a COMSOL Access account that is associated with a valid COMSOL license to download the MPH-files.

### Knudsen Minimum

When a constant pressure difference drives flow through a narrow constriction between parallel plates (or through a cylindrical tube), the flow rate exhibits a characteristic minimum as the absolute pressure at the inlet is reduced. This phenomenon is commonly referred to as Knudsen’s minimum, and occurs as a result of the rarefaction of the gas. The observation of a minimum in flow rate for ...

### Star-Shaped Microchannel

This model presents a time-dependent study of a microchannel that is used to infuse and flush another piece of equipment with a fluid. The pressure at the five inlets varies sinusoidally as functions of time, and the velocity vector at the outlet is studied. The model uses an extruded prism mesh, which reduces the computational time and memory requirements.

### Optimization of a Tesla Microvalve

This model performs a topological optimization for a Tesla microvalve. A Tesla microvalve inhibits backwards flow using friction forces rather than moving parts. The design can be optimized by distributing a specific amount of material within the modeling domain. The goal is to maximize the ratio of the pressure drop for the forwards and backwards flow across the device.

### Lamella Mixer

At the macroscopic level, systems usually mix fluids using mechanical actuators or turbulent 3D flow. At the microscale level, however, neither of these approaches is practical or even possible. This model demonstrates the mixing of fluids using laminar-layered flow in a MEMS mixer. This model analyzes the steady-state condition of the fluid flow as well as the convection and diffusion of a ...

### Viscous Catenary

The catenary is the geometrical shape that corresponds to the curve followed by an idealized chain or cable supported at both ends and hanging under its own weight. The viscous catenary problem describes the motion of a cylinder of highly viscous fluid, supported at its ends as it flows under gravity. In the last decade this problem has generated significant theoretical and experimental interest ...

### Rotating Channel

A lab-on-a-chip platform can be realized on a rotating disc by designing channels and other features to use the Coriolis or centrifugal forces to manipulate the flow. These forces are controlled by changing the angular velocity of the disc, so the platform is programmed by using a controlled sequence of angular velocities. In a microchannel, the centrifugal force induces a parabolic flow profile ...

### Slip Flow Benchmark

This model is a benchmark model for the Slip Flow interface. It is based on both analytic and numeric calculations. Air at atmospheric pressure flows through a conducting micro-channel connecting two reservoirs maintained at different temperatures. A flow between the two reservoirs develops as a result of thermal creep along the channel wall, which in turn produces a pressure gradient. At steady ...

### Optimizing Band Dispersion in an Electroosmotic Flow Through a Curved Microchannel

This model studies the dispersion of neutral species band through curved microchannel in an Electroosmotic flow (EOF) . Using Optimization module, geometric optimization is carried out to minimize the curve-induced dispersion.The central idea is to parametrically represent the geometry by Bézier curves and these geometric parameters are further treated as optimization parameters in the ...

### Split and Recombine Mixer Benchmark

This example models a split and recombine mixer channel in which a tracer fluid is introduced and mixed by multi-lamination. Diffusion is removed from the model using an extremely low diffusion coefficient so that any numerical diffusion can be studied in the lamination interfaces. The results compare well with Glatzel et al (Ref 1.) in both the lamination patterns and total pressure drop ...

### Buoyancy–driven μPCR for DNA Amplification

Polymerase chain reaction (PCR) is one of the most effective methods in molecular biology, medical diagnostics, and biochemical engineering in amplifying a specific sequence of DNA. There has been a great interest in developing portable PCR-based lab-on-a-chip systems for point-of-care applications and one strategy that seems very promising is natural convection-based PCR. This model studies ...

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