Discussion Forum

Hi

sometimes COMSOL proposes plot settings that do not correspond to the type of geoemtry you have, then you must open the corresponding plot node and change the variable names, typically switch the x,y,z,r or whatever vector component suffixes

This is a postprocessing command, and no need to resolve

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Good luck
Ivar

Thanks for your quick response Ivar! I must still be missing something since I do not get it to work even with your advise. When using 2D-axial {x,y} does not seem to exist. The only define coordinates in the model is {r,z}, not even {phi} seems to exist. However, the proposal when plotting total heat flux for the 3D-model generated by the symmetry is:
x-component: ht.tfluxr
y-component: ht.tfluxphi
z-component: ht.tfluxz

I can't change it to:
x-component: ht.tfluxx
y-component: ht.tfluxy
z-component: ht.tfluxz

Since comsol gives the message:
"Cannot evaluate expression.
Failed to evaluate variable.
- Variable: ht.tfuxx
- Geometry: 1
etc..."

Where am I thinking wrong? I also tried to plot {nx,ny,nz} but i get the same error message for nx.

Any idea?

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Thanks
Petter

Hi

what about rereading some of the docs user manual on 2D-axi (I preconise to index the PDF and to do searches thereon). You will then see that 2D uses (x-y) as (horizontal respectively vertical 2D) coordinates, but in 2D-axi these are renamed (r-z) that is "why" you need to do the mapping x=>r y=>z but once you have got this trick its easy ;)

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Good luck
Ivar

Hi,

This is a known limitation when revolving a 2D axisymmetric solution into 3D using a Revolution 2D data set and then visualizing vector fields in 3D. But there is a way to get access to the angle phi and convert the cylindrical components into Cartesian components:

In the settings window for the Revolution 2D data set node, under Advanced, select the "Define variables" check box to define the variables rev1phi for the angle phi. You can then (after re-solving or updating the solution), use the following expressions in the text fields for the x, y, and z components:

ht.tfluxr*cos(rev1phi)
ht.tfluxr*sin(rev1phi)
ht.tfluxz

Best regards,
Magnus Ringh, COMSOL

Hi again,

In fact, no re-solving or update of the solution is required.

Best regards,
Magnus Ringh, COMSOL

Thanks! :D

Hi Magnus

Thanks, I hadnt tought of that one :)

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Good luck
Ivar