1D COMSOL Domain Implementation

In summary, the person is having difficulty solving a problem with multiple subdomains and equations. They are trying to find a way to either use overlapping subdomains or have different models for each subdomain in order to avoid singular matrices. They have found a potential solution and will test it out.
  • #1
womfalcs3
62
5
Hello,

This is the first time I'm using COMSOL on a problem where I have multiple subdomains within the domain. Previously, I have only been using one domain/one set of equations/Two global sets of BC's.

I've been having a hard time thinking of a solution to my problem.

I have 3 subdomains, and all have their own set of ODE's and BC's. (They're really PDE's, but I'm going to assume stead-state for the time-being until I get it to work. I want to see the steady state solutions anyway as well.)

The problem comes in that in the first and third subdomains, I have 3 equations each to solve. In the middle subdomain, I have 7 equations to solve.

They are all heavily coupled, but the system is homogeneous and linear. So I have a total of 13 dependent variables.

Is there a way to either:

- Use overlapping subdomains so that I can have 3 subdomains in the middle rather than just one?
- Have the first and third subdomains have a model for 3 equations each, and the middle one have a model for 7 equations?

Because I can't do all 13 at once, as that gives me singular matrices during the finite element assembly.



I am currently using a 1D PDE stationary model in the coefficient form with all the transient term coefficients set to 0 for the time being.
 
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  • #2
I think I may have figured it out. I'll use it and see how the results go.

I'm trying to have 3 separate PDE models, and activating each one in one of the subdomains.
 

1. What is a 1D COMSOL domain implementation?

A 1D COMSOL domain implementation is a simulation technique used in the COMSOL Multiphysics software to model and analyze one-dimensional systems. It involves defining a one-dimensional domain and applying appropriate boundary conditions to simulate the behavior of the system.

2. How is a 1D COMSOL domain defined?

A 1D COMSOL domain is defined by specifying the geometry, material properties, and boundary conditions of the system. This can be done through the COMSOL GUI or by using the COMSOL API to write code.

3. What types of systems can be simulated using a 1D COMSOL domain implementation?

A 1D COMSOL domain can be used to simulate a wide range of physical systems, such as heat transfer, fluid flow, electromagnetics, and structural mechanics. It is particularly useful for systems with one dominant dimension, such as heat transfer through a pipe or a beam under bending.

4. What are some advantages of using a 1D COMSOL domain implementation?

One advantage of using a 1D COMSOL domain implementation is that it simplifies the modeling process and reduces computational resources required compared to 2D or 3D simulations. It also allows for a more focused analysis of a specific dimension of a system, without the complexities of a full 3D model.

5. What are some limitations of a 1D COMSOL domain implementation?

One limitation of a 1D COMSOL domain implementation is that it may not accurately capture the behavior of a system that is inherently three-dimensional. It also may not be suitable for systems with complex geometries or boundary conditions that cannot be simplified to one dimension. In these cases, a 2D or 3D COMSOL domain implementation may be more appropriate.

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