Discussion Forum

John,

my experience with streamlines is that the start points in most cases need to be defined manually. Otherwise Comsol chooses them in a way that is not compatible with the model's symmetry and this will result in such a messy picture. For plotting a profile I would recommend to use slices or multislices in a 3D plot.

Cheers Edgar

Thanks for the quick response. How can I define more than one starting point? Or can I only define one starting point per streamline plot. I used the uniform density and the streamline plot is now more like it should be, but still not very symmetrically. The multislice feature is nice, but it is not what I want. I want to get a plot of the magnetic field gradient along the y-axis like it is done for the Helmholtz Coil here https://www.comsol.com/blogs/plotting-spatial-derivatives-magnetic-field/. I followed all the steps but my plot still remains empty.

Kind regards, John

Check the interface. You can define an array of start point coordinates. Difficult to help with the plot without the model.

After the holidays I am back doing my simulation. I attached the file, because I still have questions to the plot. I defined 3D Cut Lines and plotted the Bz component of the magnetic field for them. Are there any options to get a smoother (more accurate) plot? I also expected the peak of the Bz component for each cut line much higher than it is shown in the plot. I am not sure yet, if I forgot something in my simlation or my calculations are wrong. I am gonna re-check this with another software.

Kind regards, And a happy new year everybody! John

John,

you probably need a better resolved mesh between the magnets. Your model isn't comprising current, so you can use mfnc instead of mf. You can also get your air ball much smaller if you use an infinite domain around the quadrupole.

Cheers Edgar