[Nek5000-users] How to change the x y z coordinates to be polar

[nek5000-users at lists.mcs.anl.gov]

Hi,
yes, you can rotate the stress tensor (already averaged in time and 
axial direction) into the radial and azimuthal directions; then do the 
azimuthal average, and finally go to the disturbance quantities. The 
rotations can be done in various ways; I typically just write the 
complete rotation matrix which can be constructed either using vector 
identities, or simply with sine and cosine.

Philipp

On 2018-01-18 21:06, nek5000-users at lists.mcs.anl.gov wrote:
> 
> Dear Jian,
> 
> 
> Normally I would write down the quantity of interest, e.g.,  <ur',ur'>, 
> then expand <ur>, etc., in terms of (ux,uy,uz).   When you do the small 
> bit of vector manipulations it will be clear what you need to compute. 
> Note that [ux,uy,uz]=R*[ur,ut,uz] (ut=utheta),and 
> [ur,ut,uz]=R'[ux,uy,uz], with R*R'=I.
> 
> 
> hth
> 
> 
> Paul
> 
> 
> ------------------------------------------------------------------------
> *From:* Nek5000-users <nek5000-users-bounces at lists.mcs.anl.gov> on 
> behalf of nek5000-users at lists.mcs.anl.gov <nek5000-users at lists.mcs.anl.gov>
> *Sent:* Thursday, January 18, 2018 12:40:34 PM
> *To:* nek5000-users at lists.mcs.anl.gov
> *Subject:* Re: [Nek5000-users] How to change the x y z coordinates to be 
> polar
> Hi Philipp,
> 
> Thanks for your reply. Currently I have the mean statistics. Can I 
> change the averaged velocities and velocities square to be based on 
> polar coordinates, then have the rms in radial and azimuthal?  Or I need 
> to change the coordinate firstly before the averaging.
> 
> Kind regards,
> 
> Jian
> 
> 
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