What Happens If I Use 2 Different Unit Systems in 1 Simulation?

Amit Patil December 6, 2017

Measurements and units make our professional and personal lives orderly and systematic. Different unit systems have been used over time, but today there are two dominant systems: the metric and English unit systems. What happens when both unit systems are used for the same application? In this blog post, we will shed light on two historical disasters brought about by the use of different unit systems and highlight unique features of the COMSOL Multiphysics® software for handling different unit systems.

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Uttam Pal December 4, 2017

On a bright evening in 1669, Professor Erasmus Bartholinus looked through a piece of an Icelandic calcite crystal he had placed onto a bench. He observed when he covered text on the bench with the stone, it appeared as a double image. The observed optical phenomenon, called birefringence, involves a beam of light that splits into two parallel beams while emerging out of a crystal. Here, we demonstrate a modeling approach for this effect.

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Walter Frei November 30, 2017

To fillet or not to fillet, that is the question (that can bedevil the multiphysics analyst). When building finite element models, sharp edges can lead to local singularities and fields that are nonconvergent with mesh refinement. Rounding off these sharp edges by adding a fillet avoids this singularity. As it turns out, in many multiphysics models, these sharp edges and the resultant singularities do not necessarily negatively affect the results. Let’s find out more.

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Rasmus Karlsson November 27, 2017

Wet chemical etching is used to form patterns on surfaces, with applications including the production of integrated circuits, MEMS devices, and pressure sensors. This process has been around for hundreds of years, and was a favorite method of Old Master Rembrandt van Rijn. The optimization of chemical etching was historically a matter of trial and error, but in this blog post, we’ll show how to model the process in the COMSOL Multiphysics® software.

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Ajit Bhuddi November 8, 2017

Suppose you have a very long system with a constant cross section: a fluid-filled pipe. Modeling this system is computationally expensive and time consuming. Using a guided wave propagation approach, you can model a cross section of the system and compute the guided waves along it. You can represent such waves by means of dispersion curves. Here, we discuss a coupled analysis considering air and water as the internal fluids. We also analyze the system dynamics using dispersion curves.

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Mats Danielsson November 2, 2017

In structural mechanics, there may be situations when you want to implement your own material model. The COMSOL Multiphysics® software gives you the option to program your own material model in C code. The compiled code can then be called from the program using the External Material feature. Here, we demonstrate how to implement an external material model and then use it in an example analysis.

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Friedrich Maier October 19, 2017

Optimization is an efficient way to gain deeper knowledge of a model. Much like the different flowers in a colorful bouquet, you can perform a variety of different optimization projects using the Optimization Module. However, parameter estimation is also a widely used technique. Such an analysis is usually set as a least-squares problem based on measured data, but for a clear and unique answer, you might need multiple measurements. Today, learn how to estimate parameters using a multiparameter data set.

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Mats Danielsson October 11, 2017

The trebuchet is a large siege weapon that you might recognize from movies set in the Middle Ages or fantasy worlds. This weapon is built on the idea of converting potential energy into kinetic energy to hurl a projectile over a large distance. Simple as it seems, the trebuchet is a complicated dynamical system. In this blog post, we will build a simplified model of a counterweight trebuchet using the Multibody Dynamics Module and examine some of its design features.

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Edmund Dickinson October 10, 2017

In a previous blog post, we discussed why surfaces are special in chemical reactors. In this blog post, we’ll see how surface area is maximized in reactor structures such as pellet beds, and how we can simply and accurately simulate fixed-bed reactors in spite of their local geometric complexity and the importance of microscopic diffusion.

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Guest Linus Fagerberg October 3, 2017

Guest blogger Linus Fagerberg from Lightness by Design picks up where he left off in his previous blog post to discuss how radiated sound depends on the shell thickness of a muffler. Here, we discuss different entities for gauging the performance of mufflers. One important parameter is the thickness of the muffler’s casing and how this affects its performance. By performing acoustic-structure interaction simulations, we can see how shell thickness affects muffler performance.

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Andrew Young September 27, 2017

When simulating flow in porous media, it can be efficient to simplify the geometric complexity of the real porous material using a homogenized macroscale approach. But what if we don’t know what the effective macroscopic properties are? Here, we look at how to extract the macroscopic flow properties of porosity and permeability from a fully resolved microscale submodel.

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