Have you checked the comsol tutorial? s. https://www.comsol.de/model/dielectrophoretic-separation-of-platelets-from-red-blood-cells-17013

If you are using massless equations in your simulation, you can define drag and dielectrophoretic movement at 'particle properties' when using the particle tracing module/physics.

Dear Jasper,

Thank you for your reply.

Yes. Indeed, I have added drag and dielectrophoretic forces in "Particle tracing' module. All I just want to do is to find the value of these forces on a line. Is it possible?

Of course you can export your data. This guide should be helpful https://cdn.comsol.com/offers/COMSOL_EssentialsOfPostprocessingAndVisualization_53a_v4.pdf . If this does not help check the comsol documentation and their video tutorials.

One way to create your desired line is using Dataset-->Cut line 2D. This dataset can easily be plotted or exported afterwards.

Unfortunately, I tried this method in the first place, but it did not work. I added a "Cut line 2d" and tried to compute the variation of the mentioned forces on this line, but COMSOL shows some errors. To add, I used the built-in variables of COMSOL.

Ah okay, then you are probably using the Newtonian formulation of the equations. I think in this case there is no other way (as far as I know) than to manually write down the equations in the expression field and then export/plot the data. However, doing so the drag force might not be calculated correctly, because you do not know the relative velocity of a particle at a position but only the fluid velocity. For the DEP force this should work just fine.

Thank you Jasper. I will try your proposed solution. If I use the massless form, Would I be able to extract these data?

When using massless form you are most probably using the steady state formula for the particle velocity. Which in your case consists of the velocity of the fluid (due to drag) and the velocity due to the DEP force. You can just copy and paste this formula into your export/plot window.