#### All posts by Walter Frei

#### Getting the Most out of Client-Server Mode

When using COMSOL Multiphysics on a Floating Network License, it is possible to use the Client-Server mode of operation to access remote computing resources for solving large models, while still using the graphics card on a local machine to display graphics. This can have some significant advantages, so let’s look at Client-Server mode in more detail.

#### How to Integrate Functions Without Knowing the Limits of the Integral

We all know that COMSOL Multiphysics can take partial derivatives. After all, it solves partial differential equations via the finite element method. Did you know that you can also solve integrals? That alone shouldn’t be very surprising, since solving finite element problems requires that you integrate functions. The COMSOL software architecture allows you to do a bit more than just evaluate an integral; you can also solve problems where you don’t know the limits of the integral! Here’s how.

#### What Kinds of FSI Problems Can COMSOL Multiphysics Solve?

One of the questions we get asked all the time is: “Can I use COMSOL Multiphysics for solving my fluid-structure interactions problems?” Of course the answer is yes, so let’s talk a little about the various fluid-structure interaction (FSI) modeling techniques. Along the way, we will introduce the add-on modules you will need for these various types of analyses.

#### Modeling the Hydrostatic Pressure of a Fluid in a Deformable Container

In a previous posting, we looked at computing and controlling the volume of a cavity filled with an incompressible fluid, which solved for the static deformation of a fluid-filled rubber seal. In that example, we did not explicitly model the fluid, but added an equation to solve for the pressure, assuming incompressibility of the fluid. Here, we will extend this approach and include the hydrostatic pressure of the fluid in the deforming container.

#### Computing the Impedance of a Corrugated Waveguide

It is well-known that you can use the RF Module to compute the impedance of lossless transmission line structures, such as coaxial cables of uniform cross section. But did you know that you can also compute an effective impedance for waveguides with non-uniform cross section? Let’s find out how!

#### Optimizing Heater Power for Thermal Processing

COMSOL’s Optimization Module is a powerful tool for improving the performance of your devices and systems. Here, we will look at optimizing the power applied to two heaters in a flow channel with the objective of heating up the fluid as much as possible as it passes through the channel, while constraining the peak temperature at the heaters themselves. One application of this technique is improving the efficiency of thermal processes.

#### Implementing a Simple Temperature Controller with a Component Coupling

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.

#### Computing and Controlling the Volume of a Cavity

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 […]