Mechanical

Nancy Bannach | March 11, 2014

A lot of materials have anisotropic properties and, in many cases, the anisotropy follows the shape of the material. COMSOL Multiphysics offers different methods for defining curvilinear coordinate systems. Here, we discuss the concepts of each and when to use which method.

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Henrik Sönnerlind | March 7, 2014

Buckling instability is a treacherous phenomenon in structural engineering, where a small increase in the load can lead to a sudden catastrophic failure. In this blog post, we will investigate some classes of buckling problems and how they can be analyzed.

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Gerard Hegemans | March 4, 2014

Cars come with either an automatic gearbox or a manually operated one, a stick shift. With a manual gearbox, we use the stick shifter very frequently while driving the car, yet we hardly ever think about the way the mechanism works. Here, we investigate how it works and what forces are acting on it when submitted to a very common load case — selecting first gear — with the help of a COMSOL Multibody Dynamics model of the gearshift mechanism.

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Mads Herring Jensen | February 28, 2014

Previously, we introduced the theory behind thermoacoustics. Here, I will go deeper into modeling acoustics with the Thermoacoustic interface in COMSOL Multiphysics and show you some tips and tricks on how to do this.

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Mads Herring Jensen | February 27, 2014

When sound propagates in structures and geometries with small dimensions, the sound waves become attenuated because of thermal and viscous losses. More specifically, the losses occur in the acoustic thermal and viscous boundary layers near the walls. This is a known phenomenon that needs to be included when studying and simulating systems affected by these losses in order to model these systems correctly and to match measurements.

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Ahsan Munir | February 26, 2014

DNA is a complex molecule that contains instructions for life and often referred to as a “digital fingerprint” or code telling a cell what to do. DNA is often the only means for accurate testing and identification of biomolecules, cells, or even an entire person during forensic investigations. The need to be able to test for DNA, as quickly as possible, and even at the site where the sample is taken, is becoming more and more important.

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Walter Frei | February 11, 2014

When solving a thermal processing problem, such as the heating or cooling of a part, it is desirable to change the heating, or cooling, based upon the computed solution. That is, we may want to include a feedback loop into our model. In this article, we will set up a feedback loop using a component coupling to turn a heat load on or off depending upon the temperature of the part being heated.

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Lexi Carver | February 4, 2014

Keeping the inside of a building at a comfortable temperature requires well-designed windows to keep heat out during the summer and heat in during the winter. Let’s take a look at how windows provide thermal insulation and how they carry heat (or not) between the inside of a building and the outdoors.

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Walter Frei | February 3, 2014

There are various ways of handling interactions between fluids and solids in COMSOL. You can, for example, explicitly model the fluid using the full Navier-Stokes equations for the pressure and fluid velocity fields. Although that can be a very accurate approach, it’s much more expensive than is needed for certain types of Fluid-Structure Interaction (FSI) problems. Here, we’ll introduce a method for modeling enclosed volumes containing incompressible fluids, under the additional assumption that the momentum and energy transfer via the […]

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Alexandra Foley | January 15, 2014

With shrinking electronic devices and ever-increasing power densities, efficient thermal management is at the heart of many R&D activities for electronics engineers. When developing complete systems containing multiple components, designs can become rather complex. An example of such a design would be a computer power supply unit (PSU), which can include not only electronics, but also multiple heat sinks, cooling fans, perforated grilles, and other large components — all within a small enclosure. In this blog post, we will explore […]

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Nicolas Huc | January 6, 2014

In this blog post we will explain the concept of conjugate heat transfer and show you some of its applications. Conjugate heat transfer corresponds with the combination of heat transfer in solids and heat transfer in fluids. In solids, conduction often dominates whereas in fluids, convection usually dominates. Conjugate heat transfer is observed in many situations. For example, heat sinks are optimized to combine heat transfer by conduction in the heat sink with the convection in the surrounding fluid.

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