Move a 3D object in COMSOL and calculate of charge in every position

Question

I am trying to solve with Comsol the problem of the figureTwo blue big electrodes with fixed potentials V1,V2. One red small electrode that moves above the others along x axis at constant distance and voltage V0. The charge in V0 depends on the electric field at each point 8(x). I have one small electrode with a potential V0 moving along x axis above two bigger electrodes with fixed potentials V1,V2.

I can easily compute with comsol the potential and field at each point in 3D and the resulting charge in V0 electrode. However i would like to simulate this charge along the x axis and eventually map it also for z and y direction so i have a V0 charge 2D map at a fixed distance.

How can i do this in COMSOL without changing the geometry coordinates manually and computing again the charge at each point?

Thank you for your answers,

Jorge

Answer 1

I'll describe how to setup the system so that you can move V0 around. Note that this requires changing the mesh throughout the simulation. For this reason, I don't think you want a "time dependent" study but instead you want to use the "parametric sweep" option.

First, go to your Global Parameters and create a parameter called block_x_pos or whatever you want.

Go to Component → Geometry and select V0 and in the appropriate field under the "Position" tab (in the Setting Panel), write block_x_pos in the X Position. This makes that position controllable by whatever value is in block_x_pos.

Right click on the appropriate Study and select "Parametric Sweep". The purpose (as far as I know) for the Parametric Sweep is that when the geometry is changing during computation, it updates the mesh accordingly, so you don't have to do it manually through some painful repetition. Select the "Parametric Sweep" node which has now appeared. Look in the Settings Panel and find the "Study Settings" tab. Below the empty table, you'll see some arrows and a "+" sign. Click the "+". This will add a new sweep parameter to the table. Click the dropdown menu on the table and select the "time" Global Parameter. In the "Parameter Value List" field, write the range of values you'd like to have it take.

i.e. if you want the block_x_pos parameter to vary from 0 to 10 in steps of 0.1, you would write range(0, 0.1, 10). Or you could write '-3 0 1 2 4 5 9 11' and it will take those values.

Now Compute using that same Study.

When you are making plots, be sure to use the correct Solution. It will be labeled something like "Study1/ParametricSolutions1". When you select this as your "Data Set", you will find (in your Settings Panel) a new dropdown menu below the "Data Set" field called "Parametric selection (time)". You can choose to show multiple values for the "time" parameter on most plot types.