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Polar plots
Posted 26 juin 2012, 13:55 UTC−4 4 Replies
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Hi,
I want to run a COMSOL in order to find the velocity inside a tube. I used 2D axisymmetric and found the velocity in r and z direction. However, I need to find velocity in r and theta direction for the entire range of r and theta. I think I need the polar plot group but I don't know how should I used it. I will really appreciate your help.
Thanks
Negin
I want to run a COMSOL in order to find the velocity inside a tube. I used 2D axisymmetric and found the velocity in r and z direction. However, I need to find velocity in r and theta direction for the entire range of r and theta. I think I need the polar plot group but I don't know how should I used it. I will really appreciate your help.
Thanks
Negin
4 Replies Last Post 27 juin 2012, 16:47 UTC−4
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Posted:
1 decade ago
Hi
if its the third 2D-axi coordinate its "phi" (and not theta), but a 2D-axi is indepedent of "phi" so normally it's value are all 0. Els I believe you must go in 3D to get all three vector components, the you define either a cylindrical coordinate, or a psherical, or use somethin like an r=sqrt(x^2+y^2) and atan2(v,u) for a phi in the X-Y plane
--
Good luck
Ivar
if its the third 2D-axi coordinate its "phi" (and not theta), but a 2D-axi is indepedent of "phi" so normally it's value are all 0. Els I believe you must go in 3D to get all three vector components, the you define either a cylindrical coordinate, or a psherical, or use somethin like an r=sqrt(x^2+y^2) and atan2(v,u) for a phi in the X-Y plane
--
Good luck
Ivar
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Posted:
1 decade ago
Hi,
Thanks for your response. Actually it is a 2D which has only r and theta( no Phi is needed). I want to create my results in a plot which itsaxis are r and theta. So as you said Phi is zero. Just r and theta is needed. I did the exact same thing with MATLAB (r,theta) and plot my velocities in polar coordinates and I want to compare my results with COMSOL, in order to get the exact same results from both of them.
Thanks,
Negin
Thanks for your response. Actually it is a 2D which has only r and theta( no Phi is needed). I want to create my results in a plot which itsaxis are r and theta. So as you said Phi is zero. Just r and theta is needed. I did the exact same thing with MATLAB (r,theta) and plot my velocities in polar coordinates and I want to compare my results with COMSOL, in order to get the exact same results from both of them.
Thanks,
Negin
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Posted:
1 decade ago
Hi
OK I didnt cat it then, in 2D COMSOL is by default in the cartesian coordinates (x,y) but you can easily set up a cylindrical coordinate (r, theta) with coresponds to r=sqrt((x-x0)^2+(y-Y0)^2) and theta = atan2(y,x).
Either you define the two variables, or you add a cylidrical coordinate "sys2" and you access sys2.r and sys2.theta (I have a doubt about the second name pls check, I'm not by my WS ;)
Then you can generate your polar plot with r and theta (your vaiables), or the default sys2 references
--
Good luck
Ivar
OK I didnt cat it then, in 2D COMSOL is by default in the cartesian coordinates (x,y) but you can easily set up a cylindrical coordinate (r, theta) with coresponds to r=sqrt((x-x0)^2+(y-Y0)^2) and theta = atan2(y,x).
Either you define the two variables, or you add a cylidrical coordinate "sys2" and you access sys2.r and sys2.theta (I have a doubt about the second name pls check, I'm not by my WS ;)
Then you can generate your polar plot with r and theta (your vaiables), or the default sys2 references
--
Good luck
Ivar
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Posted:
1 decade ago
Thanks for your answer
Negin
Negin