# 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.

### Laminar Static Particle Mixer Designer

In static mixers, a fluid is pumped through a pipe containing stationary mixing blades. This mixing technique is well suited for laminar flow mixing, because it generates only small pressure losses in this flow regime. When a fluid is pumped through the channel, the alternating directions of the cross-sectional blades mix the fluid as it passes along the length of the channel. The static mixing ...

### Inertial Focusing Between Two Parallel Walls

For more than 50 years, it has been known that neutrally buoyant particles in a flow channel tend to converge to specific locations in the channel cross section. For a cylindrical pipe, or two parallel planes carrying a Poiseuille flow, the equilibrium position is about 0.6 times the pipe radius, or a distance from parallel walls of about 0.2 times the channel width, respectively. This is called ...

### Dispersion of Heavy Particles in a Turbulent Channel Flow

In this benchmark model, solid particles are released in a fully developed turbulent channel flow. The particles are subjected to a drag force that includes contributions from the fluid turbulence, implemented using a Continuous Random Walk (CRW) model. Because the turbulence in the channel is anisotropic, particles with significant inertia tend to cluster near the channel walls, while very ...

### Ideal Cloak

This model demonstrates the use of optical tracing for studying optically large gradient-index structures with anisotropic optical properties. Additionally, the model introduces a smoothing technique for handling discontinuities of refractive index on curved surfaces, which are typical in conventional optical devices such as lenses.

### Thermophoresis

When a temperature gradient in a gas exists, suspended particles will tend to move from regions of high temperature to low. The force which produces this effect is called the thermophoretic force. Gas molecules colliding with a particle from the hot side have a higher velocity than the cold side, which results in a net force towards cold areas. This effect can be exploited to create thermal ...

### Relativistic Diverging Electron Beam

When modeling the propagation of charged particle beams at high currents and relativistic speeds, the space charge and beam current create significant electric and magnetic forces that tend to expand and focus the beam, respectively. The *Charged Particle Tracing* interface uses an iterative procedure, in this example, to efficiently compute the strongly coupled particle trajectories and ...

### Ion Funnel

An electrodynamic ion funnel provides an efficient means of transferring ions from regions of high pressure to high vacuum. The ion funnel can couple devices which generally operate at pressures of different orders of magnitude, such as ion mobility spectrometers and mass spectrometers, allowing mixtures of ionized gases to be separated and analyzed while minimizing losses. This model ...

### 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. ...