# Help to convert the cartesian grid/domain to cylindrical grid/domain
**URL:** https://discourse.paraview.org/t/help-to-convert-the-cartesian-grid-domain-to-cylindrical-grid-domain/6086
**Category:** ParaView Support
**Created:** [December 17, 2020, 9:53am UTC](https://discourse.paraview.org/t/help-to-convert-the-cartesian-grid-domain-to-cylindrical-grid-domain/6086 "2020-12-17T09:53:47Z")
**Posts on this page:** 15
**Page:** 1
### Author:  [@proxy](https://discourse.paraview.org/u/proxy)
#### Post date: [December 17, 2020, 9:53am UTC](https://discourse.paraview.org/t/help-to-convert-the-cartesian-grid-domain-to-cylindrical-grid-domain/6086/1 "2020-12-17T09:53:47Z")
Hello All,
Is there any easy way to convert the Cartesian grid/domain to cylindrical grid/domain. I have created a Cartesian grid/domain for my simulation, to understand, analyze and compare the flow/data I want to convert this Cartesian grid/domain into cylindrical system.
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### Author:  [@proxy](https://discourse.paraview.org/u/proxy)
#### Post date: [December 18, 2020, 8:22am UTC](https://discourse.paraview.org/t/help-to-convert-the-cartesian-grid-domain-to-cylindrical-grid-domain/6086/2 "2020-12-18T08:22:46Z")
Hello again,
Sorry for my unclear question, to be little more specific, I need a slice (in Cartesian grid/domain ) at an angle of 40 degree from vertical and in that slice I need to see the radial and tangential component of velocity field and need to calculate the vorticity. I follow these steps:
1. To take a slice at an angle of 40 degree from the vertical axis (x normal), I modified the slice normal values as (1,-0.839,0). While considering the value -0.839 I assume that -1 is corresponding to 45 degree therefore using linear interpolation, I calculated the angle corresponding to 40 degree. Is that correct?
2. To get the uradial I used the calculator: uradial=v_cos(3.14_40/180)+u_sin(3.14_40/180), similarly for utheta: utheta=-v_sin(3.14_40/180)+u_cos(3.14_40/180), for getting the coordinates transformed:
r=y_cos(3.14_40/180)+x_sin(3.14_40/180) and \theta=-y_sin(3.14_40/180)+x_cos(3.14_40/180)
Now I need the vorticity in the \theta direction which is: \partial(uz)/\partial®-\partial(uradial)/\partial(z). But simultaneously I could not access the new calculated values of uradial and radial coordinate ®. Is there any way to do that? Am I on the right direction ? Any suggestion/comment will be a great help. Thanks in advance.
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [December 18, 2020, 2:44pm UTC](https://discourse.paraview.org/t/help-to-convert-the-cartesian-grid-domain-to-cylindrical-grid-domain/6086/3 "2020-12-18T14:44:06Z")
Sounds like a job for the Calculator ?
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### Author:  [@proxy](https://discourse.paraview.org/u/proxy)
#### Post date: [December 20, 2020, 5:55am UTC](https://discourse.paraview.org/t/help-to-convert-the-cartesian-grid-domain-to-cylindrical-grid-domain/6086/4 "2020-12-20T05:55:17Z")
Hello Mathieu Westphal,
Thanks for your insight, but as I had mentioned in the previous post that “simultaneously” I need the two variables that I calculated, but at the time for doing calculations (for calculating the vorticity in \theta direction) it is showing single variable . In the previous post I had detailed my problem, could you kindly re-visit my issue. Any further comment/suggestion will be a kind help.
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [December 20, 2020, 10:09am UTC](https://discourse.paraview.org/t/help-to-convert-the-cartesian-grid-domain-to-cylindrical-grid-domain/6086/5 "2020-12-20T10:09:54Z")
There is no reason that you shouldn’t be able to acess both variable after computing. Please share a screenshot.
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### Author:  [@proxy](https://discourse.paraview.org/u/proxy)
#### Post date: [December 20, 2020, 10:40am UTC](https://discourse.paraview.org/t/help-to-convert-the-cartesian-grid-domain-to-cylindrical-grid-domain/6086/6 "2020-12-20T10:40:52Z")
Thanks for your prompt reply, in the screenshot you can see that I calculated the variables that are required to calculate the \theta\_vorticity but when I am actually trying to calculate this variable (vorticity\_theta) named as Calculaotr1, I could not find them in the Scalars list. If say particularly I select the calculator\_r while calculating the Calculator1 then only the variable “r” is available. hope I am clear this time about my problem.
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [December 21, 2020, 10:51am UTC](https://discourse.paraview.org/t/help-to-convert-the-cartesian-grid-domain-to-cylindrical-grid-domain/6086/7 "2020-12-21T10:51:55Z")
Connect each calculator to the previous calculator instead of connecting to the slice everytime
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### Author:  [@proxy](https://discourse.paraview.org/u/proxy)
#### Post date: [December 21, 2020, 12:22pm UTC](https://discourse.paraview.org/t/help-to-convert-the-cartesian-grid-domain-to-cylindrical-grid-domain/6086/8 "2020-12-21T12:22:37Z")
Wow, it worked, thanks a lot. I guess it was a silly mistake from my side, I should have resolved that, sorry for bothering you. Also from the derived scalars like r, \theta, u\_\radial and u\_\theta I need to find out the vorticity: \partial{uz}/\partial{r}-\partial{uradial}/\partial{z}, which essentially needs the derivative of the derived quantities/scalars. Also is it possible to draw the vectors from the derived velocity fields u\_radial and u\_theta? Thanks again for your consistent and prompt help.
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [December 21, 2020, 1:47pm UTC](https://discourse.paraview.org/t/help-to-convert-the-cartesian-grid-domain-to-cylindrical-grid-domain/6086/9 "2020-12-21T13:47:51Z")
> which essentially needs the derivative of the derived quantities/scalars.
Im afraid this is not easy to compute directly
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### Author:  [@proxy](https://discourse.paraview.org/u/proxy)
#### Post date: [December 21, 2020, 1:50pm UTC](https://discourse.paraview.org/t/help-to-convert-the-cartesian-grid-domain-to-cylindrical-grid-domain/6086/10 "2020-12-21T13:50:45Z")
Ok, thanks a lot for the clarification. Plotting the vectors out of the newly computed scalars: u\_\theta and u\_\radial, would be straightforward?
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [December 21, 2020, 1:53pm UTC](https://discourse.paraview.org/t/help-to-convert-the-cartesian-grid-domain-to-cylindrical-grid-domain/6086/11 "2020-12-21T13:53:18Z")
Sure, just use PlotData filter.
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### Author:  [@proxy](https://discourse.paraview.org/u/proxy)
#### Post date: [December 21, 2020, 1:57pm UTC](https://discourse.paraview.org/t/help-to-convert-the-cartesian-grid-domain-to-cylindrical-grid-domain/6086/12 "2020-12-21T13:57:47Z")
No no, sorry what I mean is that could I show the vectors representing the u\_radial and u\_theta, instead of the native u,v, and w?
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [December 21, 2020, 2:05pm UTC](https://discourse.paraview.org/t/help-to-convert-the-cartesian-grid-domain-to-cylindrical-grid-domain/6086/13 "2020-12-21T14:05:06Z")
Did you compute it ?
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### Author:  [@proxy](https://discourse.paraview.org/u/proxy)
#### Post date: [December 21, 2020, 2:10pm UTC](https://discourse.paraview.org/t/help-to-convert-the-cartesian-grid-domain-to-cylindrical-grid-domain/6086/14 "2020-12-21T14:10:51Z")
Sorry I didn’t understand, you mean–the vorticity or the PlotData filter or the vectors? I calculated the u\_radial and u\_theta and wanted to see the vectors representing the u\_radial and u\_theta, instead of original u, v and w. I plotted the PlotData filter using the newly calculated scalars radial, theta, u\_radial, u\_theta.
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [December 21, 2020, 2:16pm UTC](https://discourse.paraview.org/t/help-to-convert-the-cartesian-grid-domain-to-cylindrical-grid-domain/6086/15 "2020-12-21T14:16:16Z")
If you computed the u\_radial and u\_theta values, then you should be able to show them without any issues.