All posts by Walter Frei
Part 2: Modeling the Harmonic Excitations of Nonlinear Systems
Extending our discussion on modeling the harmonic excitations of linear systems, we will now shift focus to nonlinear systems. We will look at problems where the loading on the system has some sinusoidal components as well as cases where the material properties or loads and constraints depend directly on the solution. As you will see, COMSOL Multiphysics can address these apparently nonlinear cases with some very efficient solution algorithms. Let’s find out how.
Part 1: Modeling the Harmonic Excitations of Linear Systems
In many engineering situations, we can assume that excitations on the system of interest and the responses are sinusoidal over time. When this assumption holds, we can use a so-called frequency-domain analysis, which leads to some very efficient solution techniques. Let’s go over a few basic concepts and the conditions under which we can make this assumption, while exploring various solution approaches to take.
How to Implement a Delay in Your Thermostat Simulation
Thermostats are used in most homes for controlling furnaces and air conditioners to maintain a comfortable interior temperature. A simple thermostat controlling a heater will have on and off setpoints. Such a control scheme is easy to implement within COMSOL Multiphysics using the Events interface, as presented in a previous blog post. Today, we will expand this technique to include a delay, a time lag between turning the heater on or off, in a thermostat simulation.
Thermal Modeling of the Air Flow Inside and Around Your House
Have you ever wanted to quickly predict the temperature of an enclosed structure that is exposed to ambient environmental conditions, such as your house? The temperature inside depends on the surrounding air temperature, wind speed, and solar loads, all of which have significant variability. For simplicity, we often also want to approximate the inside air as well-mixed. Today, we will discuss the tools in the COMSOL Multiphysics® software that help you quickly build such thermal models.
Exporting Meshes and Solutions Using the Application Builder
Have you ever wanted to write out mesh and analysis data from COMSOL Multiphysics into a text file? You may want to do this when passing information to another software program or even just into a spreadsheet. You often want to customize the exact format in which such data is written, depending upon the needs of the other tools with which you are working. This is very easy to do with the Application Builder. Let’s find out how!
Modeling Thermal Ablation for Material Removal
Whenever solid materials are heated enough, they will melt and then vaporize to a gas. Certain materials will even go directly from the solid to the gas phase, a process referred to as sublimation or ablation. If the material is heated strongly enough, there will be significant material removal. Today, we will look at how you can model this process in COMSOL Multiphysics.
Thermal Modeling of Phase-Change Materials with Hysteresis
In today’s blog post, we will introduce a procedure for thermally modeling a material with hysteresis, which means that the melting temperature is different from the solidification temperature. Such behavior can be modeled by introducing a temperature-dependent specific heat function that is different if the material has been heated or cooled past a certain point. We can implement this behavior in COMSOL Multiphysics via the Previous Solution operator and a little bit of equation-based modeling. Let’s find out how…
How to Choose Between Boundary Conditions for Coil Modeling
Whenever you are modeling coils with the AC/DC Module in COMSOL Multiphysics, you need to consider what type of boundary conditions to use to truncate your modeling domain. In this blog post, we will introduce the different boundary conditions that you can use and how to choose between them.
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