Flow in an Airlift Loop Reactor
This example illustrates multiphase flow modeling in an airlift loop reactor. The reactor is filled with water and air bubbles are injected at the bottom through two frits. Due to buoyancy, the bubbles rise, inducing a circulating motion of the liquid. The model specifically investigates the effect of including bubble-induced turbulence.
Flow of Oldroyd-B Viscoelastic Fluid
Many complex fluids of interest exhibit a combination of viscous and elastic behavior under strain. Examples of such fluids are polymer solutions and melts, oil, toothpaste, and clay, among many others. The Oldroyd-B fluid presents one of the simplest constitutive models capable of describing the viscoelastic behavior of dilute polymeric solutions under general flow conditions. Despite the ...
Contaminant-Removal from Wastewater in a Secondary Clarifier by Sedimentation
Wastewater treatment is a several-step process for removing contaminants. Firstly, large, solid particles are removed through sedimentation, flotation, and filtration. And then in a second step, biological treatment causes the smaller particles to aggregate, forming so called flocs. These flocs can be more easily removed by processes such as sedimentation. In a circular secondary clarifier, ...
Turbulent Mixing of a Trace Species
This tutorial model demonstrates how mixing can be visualized in a stirred vessel by seeding a trace species from a point. The flow is modeled using the Rotating Machinery, Fluid Flow physics which solves Navier-Stokes equations on geometries with rotating parts, for example impellers. The transport of the trace species is modeled using the Transport of Diluted Species physics.
Swirl Flow Around a Rotating Disk
Swirl flow is an application that involves steady rotational flow around an axis. Rather than modeling this process in 3D, COMSOL Multiphysics provides a 2D axisymmetric interface where the flow in the rotational direction is still included in the equations. This example shows the effect of a rotating cylinder on the flow in a container. Such applications are often used in chemical kinetic ...
Phase Separation
Phase separation occurs when a binary system is quenched from its stable, homogeneous one-phase state into the two-phase region of its phase diagram. The spontaneous separation of two immiscible fluids is sometimes referred to as spinodal decomposition. Each phase tends to separate into pure components. This benchmark model takes two initially mixed, immiscible phases and observes their ...
Bubble-induced Entrainment Between Stratified Liquid Layers
This model is a benchmark for three-phase flow commonly used in food processing, pharmaceutical industry, and chemical processing. The results are validated against data reported in the literature. A gas bubble rises through two layers of liquid, a lighter liquid resting on top of a heavier one. As the bubble travels from the heavier liquid, it entrains some of the heavier liquid in its wake ...
Displacement Ventilation
In general, there are two classes of ventilation: mixing ventilation and displacement ventilation. In displacement ventilation, air enters a room at the floor level and displaces warmer air to achieve the desired temperature. Heating sources in the room can include running electronic devices, or inlet jets of warm air. A potential issue with the displacement ventilation approach is that ...
Stationary Incompressible Flow over a Backstep
This tutorial model solves the incompressible Navier-Stokes equations in a backstep geometry using the Laminar Flow interface. A characteristic feature of fluid flow in geometries of this kind is the recirculation region that forms where the flow exits the narrow inlet region. The model clearly demonstrates the formation of such a region, which is best displayed by visualizing the flow ...
NACA Airfoil Optimization
The aerodynamic properties of a wing, propeller, or turbine blade are to a large extent determined by the precise shape of the airfoil that is used. The NACA Airfoil Optimization application computes the two main aerodynamic properties (the lift and drag coefficients) of a fully parameterized NACA airfoil. It can be used to visualize how changes to the airfoil thickness, camber, and chord length ...
