How to Model Supersonic Flows in COMSOL Multiphysics®

Siva Sashank Tholeti August 10, 2017

Have you ever been curious about how to model supersonic flows, like those around Concorde or fighter jets? Generally, this process requires the resolution of shocks or expansion fans in the flow. Resolving discontinuities (e.g., shock waves) requires a high resolution and the numerical stability of strongly coupled mass, momentum, and energy conservation equations for fluid flow. Let’s discuss how to model supersonic flow past a diamond airfoil, which involves resolving shocks and expansion fans.

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Caty Fairclough August 9, 2017

Studying vacuum system designs can be difficult, since some analysis methods only work when the relative speed of the gas molecules is very large compared to the velocity of the enclosing walls. This is not the case for turbomolecular pumps, which we can model and analyze using a Monte Carlo approach and the Rotating Frame feature in the COMSOL Multiphysics® software. Let’s check out one example below.

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Bjorn Sjodin August 8, 2017

The latest version of the AC/DC Module enables you to create electrostatics models that combine wires, surfaces, and solids. The technology is known as the boundary element method and can be used on its own or in combination with finite-element-method-based modeling. In this blog post, let’s see how the new functionality can be used to conveniently set up a model that includes a number of very thin spiral wires.

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Caty Fairclough August 7, 2017

Metamaterials are artificial materials with properties that rely on a particular structural design rather than chemistry. Their structure is often complicated, making these materials challenging to fabricate. Here, we present numerical research that investigates one such material — a poroelastic metamaterial (made from a single material with voids) with the ability to expand under hydrostatic pressure.

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Bridget Cunningham August 3, 2017

There are many ways to improve the frequency response of frequency-selective surfaces. However, optimizing these structures can require multiple steps. Every change to a design parameter — unit cell type, polarization, substrate properties, etc. — needs the expertise of simulation engineers. Simulation apps enable those with little or no simulation experience to run analyses for their specific stage of the design process on their own.

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Caty Fairclough August 2, 2017

When designing heat sinks, it’s important to accurately measure their cooling capacity. By modeling heat transfer in these systems, we can calculate the temperature of the electronic components. The modeling approach we use will affect the accuracy of the results and the efficiency of the simulation. In this blog post, we compare two modeling approaches for analyzing electronic chip cooling. We also discuss new features in the COMSOL Multiphysics® software that make it easier to set up heat sink geometries.

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Bridget Cunningham August 1, 2017

Helmholtz coils are used by scientists to generate uniform magnetic fields to study electromagnetism and its characteristics. These devices are used in MRI, spectroscopy, magnetoresistance measurements, and equipment calibrations. Here, we’ll look at what Helmholtz coils are, why they are important, and using a simulation-based approach to their design.

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Caty Fairclough July 31, 2017

One application of acoustic streaming (AS), the process of using sound waves to generate steady fluid motion, is adjusting grain morphology during the metal solidification process. Since ensuring the best product possible is key, engineers in the metal processing industry must improve AS, which can require costly field tests and test rigs. To see if simulation can be used to reduce this need, researchers analyzed AS treatment with the COMSOL Multiphysics® software.

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Andrew Griesmer July 27, 2017

Have you ever tried to plot multiple quantities on one graph, only to realize that the scales don’t match up? You can solve this problem by adding a second y-axis to your 1D plot to include two scales of values. In the video below, we introduce a case where you would want two y-axes. We then show you how to add a second y-axis to your graph and create helpful annotations in the COMSOL Multiphysics® software.

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Peter Yakubenko July 26, 2017

Many elongated structures can be modeled effectively using 2D representations of their cross sections. A typical assumption is the plane strain approximation, which implies that all out-of-plane strain components are zero. This assumption is valid when the out-of-plane deformation is restrained; for example, when the ends of the structure are fixed. However, in many cases, the structure is free to expand in the out-of-plane direction. Let’s discuss how to model this case, which is sometimes called generalized plane strain.

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Mads Herring Jensen July 25, 2017

Detailed modeling of the complex interaction of flow and acoustics is achieved in the COMSOL Multiphysics® software and add-on Acoustics Module using the linearized Navier-Stokes interfaces. With the release of version 5.3, the capabilities were further extended with the addition of a new stabilization scheme. This allows robust simulations of systems with acoustic properties that are modified by or depend on a turbulent background flow; e.g., automotive exhaust systems. Here, we introduce important modeling concepts and present application examples.

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