## Analyze Thin Structures Using Up and Down Operators

##### Nancy Bannach | January 12, 2016

Modeling complex geometries with thin structures can be very costly in terms of computational effort, particularly as such structures require quite a lot of mesh elements in order to resolve them. COMSOL Multiphysics provides dedicated features for modeling thin structures so that such models can be solved efficiently while maintaining accuracy. To set up and postprocess thin structures, COMSOL Multiphysics also provides specialized operators to help you consider all the relevant parameters required for accurate results.

##### 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.

##### 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!

##### Chien Liu | October 20, 2015

The shortest route between two points isn’t necessarily a straight line. If by shortest route, we mean the route that takes the least amount of time to travel from point A to point B, and the two points are at different elevations, then due to gravity, the shortest route is the brachistochrone curve. In this blog post, we demonstrate how to use built-in mathematical expressions and the Optimization Module in COMSOL Multiphysics to solve for the brachistochrone curve.

##### Temesgen Kindo | September 29, 2015

In many simulation tasks, it is necessary to transfer variables from one region of a computation domain (the source) to another region or component (the destination). In COMSOL Multiphysics, this functionality is achieved by defining a point-to-point map, called an extrusion operator, that relates a set of destination points with a set of source points. Once a mapping is established by an extrusion operator, all variables defined at the source can be accessed from the destination using the same operator.

##### Walter Frei | September 7, 2015

When using the finite element method, we often want to model solid objects that are rotating and translating within other domains. The deformed mesh interfaces in COMSOL Multiphysics can be used to model these movements. In this blog post, we will look at the modeling of large linear translations and rotations of domains within other domains, while introducing efficient modeling techniques for addressing such cases.

##### 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.

##### 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.

##### Temesgen Kindo | October 5, 2015

Previously on the blog, we introduced you to Linear Extrusion operators and demonstrated their use in mapping variables between a source and a destination. This approach, as explained earlier, is limited to cases in which the source and destination are related by affine transformations. Today, we will discuss General Extrusion operators, which are designed to handle nonlinear mappings and the mapping of variables between geometric entities of different dimensions.

##### 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.