## Using Radial Basis Functions for Surface Interpolation

##### Walter Frei March 8, 2016

Have you ever had a set of nonuniformly distributed points in a Cartesian plane that sample a surface height, such as points on the contours of a map or data points representing some material property data? If so, you probably also wanted to reconstruct, or interpolate, a continuous and smooth surface between these points. You can construct such a surface using the core capabilities of COMSOL Multiphysics by using Radial Basis Functions. Let’s find out how…

Read More##### Walter Frei March 3, 2016

One of the most common uses of the AC/DC Module is for modeling electromagnetic coils and the interactions with their surroundings. Today, we will look into one of the key concepts to keep in mind when modeling coils: closing the current loop. If your work involves modeling coils, you will need a complete understanding of this topic.

Read More##### Walter Frei March 2, 2016

Have you ever wanted to rapidly set up a COMSOL Multiphysics model with hundreds of different parts? If so, you might not want to use a graphical user interface where you manually enter dimensions and properties for each part. Generating a text file that contains all of this information offers a much faster route. Today, we will look at how you can use the Application Builder to quickly convert a text input file into a COMSOL model.

Read More##### Walter Frei February 25, 2016

If you’ve ever worked with the Terminal boundary condition in COMSOL Multiphysics, you know that this electrical boundary condition can apply a current or voltage, among other options. But did you know that you can also dynamically switch between excitation types during a transient simulation? This is useful if you are trying to model a current- or voltage-limited power supply, for example. Today, we will look at how to implement such a switching behavior.

Read More##### Walter Frei February 22, 2016

Whenever you are building a finite element model in COMSOL Multiphysics, you should be aware of the element order that is being used. This is particularly important for multiphysics models as there are some distinct benefits to using different element orders for different physics. Today, we will review the key concepts behind element order and discuss how it applies to some common multiphysics models.

Read More##### Walter Frei January 20, 2016

Radiofrequency tissue ablation is a medical procedure that uses targeted heat for a variety of medical purposes, including killing cancerous cells, shrinking collagen, and alleviating pain. The process involves applying mid- to high-frequency alternating current directly to the tissue, raising the temperature in a focused region near the applicator. We can simulate this process with COMSOL Multiphysics and the AC/DC and Heat Transfer modules. In today’s blog post, we will go over some key concepts for modeling this procedure.

Read More##### Walter Frei January 5, 2016

It has been a remarkably warm winter in Boston, but we finally got our first snowfall. As I was staring out the window earlier, I started thinking about snowflakes and how their formation cannot be easily described mathematically. However, there is one special kind of snowflake that can be simply described, known as the Koch snowflake. Today, we will look at how this shape can be built with the Application Builder in COMSOL Multiphysics.

Read More##### Walter Frei December 29, 2015

While designing a structure, have you ever been unsure of how to achieve the best shape? If so, then you will want to add a useful technique called shape optimization to your COMSOL Multiphysics modeling skill set. Today, we will discuss the concept of shape optimization and demonstrate its use through a classical problem.

Read More##### Walter Frei December 24, 2015

In this blog post, we will introduce the concept of shape optimization for adjusting part dimensions by using analytic sensitivity methods. If you have a single objective function that you want to improve, a set of geometric parameters that you want to change, as well as a set of constraints, then you can use the functionality of the Optimization Module and the Deformed Geometry interface in COMSOL Multiphysics to find the optimal structure without any remeshing. Let’s find out how!

Read More##### Walter Frei November 18, 2015

When solving a chemical species transport problem, we are often dealing with cases that have a high Péclet number, where the ratio of the advection to diffusion is very high. We may also be dealing with such problems in structures that are periodic along the flow direction, and where the flow field itself is periodic. Using COMSOL Multiphysics, we can greatly reduce our computational requirements for such problems by using General Extrusion component couplings and the Previous Solution operator.

Read More##### Walter Frei September 8, 2015

Good competitive paddling requires strength, timing, consistency, and teamwork. Initially, this may seem quite easy. Simply stick your paddle in the water and make the water go backward so that the boat moves forward. As it turns out, there are actually many different paddling strokes you can use depending on the situation.

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