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Applying cylindrical coordinate system in comsol

Posted 23 mars 2023, 01:49 UTC−4 Version 5.6 4 Replies

M Gnanasekaran
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I am studying a 3d transient model to understand the effect of combined Buoyancy-Marangoni convection in a cylindrical geometry. I want to apply the cylindrical coordinates (r, θ, a). As a solution to this, I have changed the default cartesian system (x, y,z) to cylindrical coordinates under component< definitons<cylindrical coordinates. But while postprocessing I am unable to get the resullts in (r, θ, a) coordinate systems. Eg: If we want to take the azimuthal velocity ie Vθ, in the drop down only cartisean variables are available ie Vx, Vy, Vz.

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4 Replies Last Post 27 mars 2023, 11:19 UTC−4
M Gnanasekaran
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Posted: 2 years ago 23 mars 2023, 01:50 UTC−4

I have attached a doc file that contains my doubts with images.Please go through it and suggest me some solutions.

Thank You

I have attached a doc file that contains my doubts with images.Please go through it and suggest me some solutions. Thank You
Henrik Sönnerlind COMSOL Employee

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Posted: 2 years ago 23 mars 2023, 11:04 UTC−4

The local coordinate system in the Fluid node is only used to interpret the inputs (that is, Velocity Field and possibly a nonisotropic Thermal Conductivity).

If you want to transform the velocity into a local coordinate system, you can use the Vector Transform node, found under Definitions -> Variable Utilities.

As for your second question, it is better if you can upload your model (or a similar one).

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Henrik Sönnerlind
COMSOL
The local coordinate system in the *Fluid* node is only used to interpret the inputs (that is, *Velocity Field* and possibly a nonisotropic *Thermal Conductivity*). If you want to transform the velocity into a local coordinate system, you can use the *Vector Transform* node, found under *Definitions* -> *Variable Utilities*. As for your second question, it is better if you can upload your model (or a similar one).
M Gnanasekaran
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Posted: 2 years ago 27 mars 2023, 01:47 UTC−4

Thank you for your kind suggestions.

I have used the vector transform node like you suggested. But unfortunatley I still get results in x,y,z coorinates. Can u please where I made a mistake?. I have attached the images.

Thank you for your kind suggestions. I have used the vector transform node like you suggested. But unfortunatley I still get results in x,y,z coorinates. Can u please where I made a mistake?. I have attached the images.

Attachments:

Henrik Sönnerlind COMSOL Employee

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Posted: 2 years ago 27 mars 2023, 11:19 UTC−4

a) You have not selected any input in Vector Transform. You should select the velocity vector there.
b) The result to be displayed is the variable created in Vector Transform; a name that you choose.

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Henrik Sönnerlind
COMSOL
a) You have not selected any input in *Vector Transform*. You should select the velocity vector there. b) The result to be displayed is the variable created in *Vector Transform*; a name that you choose.

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