Magnet Through Copper Tube w/ Moving Mesh

Tesla Pratt, 6/12/24 — Professor Littman

Objective: Create a magnet that moves up and down inside a copper tube using a moving mesh and successfully plot current density. 

Selected Space Dimension: 2D Asymmetric

Results: Using components of COMSOL’s Magnet Falling Through Copper Tube and Voltage Induced in a Coil by a Moving Magnet I was able to successfully apply moving meshes to the Magnetic Fields(mf) workspace.

3D and 2D Current Density Plots

Link to my model: Compressed COMSOL 6.2 file – 2D Moving Mesh

As shown above, as the magnet moves up and down inside of a metal tube, eddy currents are induced in the material surrounding the magnet. Eddy Currents occur when there are changing magnetic fields next to a solid body. 

Process:

  1. Open up the Voltage Induced in a Coil by a Moving Magnet mph file
  2. Replace the Coil for a Copper Tube
    1. Find the “Magnetic Fields (mf)” section in the Model Builder window.
    2. Delete “Coil 1”
  3. Assigning Ampere’s law to the copper tube
    1. Right click on “Magnetic Fields (mf)” and click “Ampere’s Law in Solids”
    2. Select the copper tube component 
    3. In the Label section, change the title to “Ampere’s Law Copper Tube”
  4. Assigning Ampere’s law to the magnet
    1. Create another “Ampere’s Law in Solids”
    2. Select the magnet in the selection window
    3. Find “Magnetization Model” in the settings window
    4. In the dropdown, select “Remanent Flux Density”
    5. Make sure “Remanent Flux Direction” is in the Z direction
    6. In the Label section, change the title to “Ampere’s Law Magnet”