Discussion Forum

I have a problem with my simulation in COMSOL 4.3b. I am working on a project where particles in a microchannel are driven my magnetic forces. I already successfully finished the model in 2D but in 3D I get some problems. I will describe my model (1), and two simplified versions (2) & (3).

1. --------------------------------------------------​--------------------------------------------------​
My model consists out of 2 models:

Mod1 (2D): Where the magnetic field is calculated successfully in 2D (which will later be used in Mod2 in 3D, using “General Extrusion” to map the field into 3D.)
Mod2 (3D): In this part the creeping flow of the microchannel is computed and the particle tracing as a function of the 3D magnetic field from mod1 is calculated.

The 3D mapping of the magnetic field works, however the particle tracing of Mod2 does not seem to be solved in 3D, while it is in the 3D model.

2. --------------------------------------------------​--------------------------------------------------​
When I simplify the “Study-part” of the entire model where it only solves Mod2 (the 3D part), it still doesn’t work even after clearing all solutions. The study for this simplified version is:

Study 1: Computes the stationary creeping flow from Mod2 (this works in 3D)
Study2: Computes the particle tracing from Mod2, with Values of variables not solved for Study1.

Still the same error occurs when i compute Study2.

"the stored trajectories have the wrong dimension
-Dimension: 2
-Plot: traj1 (Particle trajectories)."

while the particle tracing module is modelled in 3D.

3. --------------------------------------------------​--------------------------------------------------​
But when I delete Mod 1 (The 2D model which was also not computed in the 2nd case), so the model consists only out of Mod2 and the same study as in the 2nd case is used, the particle tracing works.

So my question, how is this possible? Do I need to set an option somewhere? Why is my particle tracing not working in the 2nd case, but when I delete mod1 and keep the same study it works in the 3th case?

Thank you in advance,
Tom Willems