RMS Velocity coordinates transform?

ray_lo · July 7, 2016, 00:54

Dear all,

I have the RMS fluctuating velocities in Cartesian coordinate taken from a FLUENT LES simulation. But I now need to check the the RMS fluctuating velocities in cylindrical coordinate.

Do anybody know how to transform RMS fluctuating velocities from Cartesian to cylindrical?

Many thanks

Ray

ray_lo · July 9, 2016, 06:08

figure it out. actually quite easy ~_~ .
I will put the answer here just for people who may need a quick answer of it.

radial:
ur_rms=sqrt(cos(theta)*cos(theta)*SQR(ux_rms)+sin( theta)*sin(theta)*SQR(uy_rms)+2*cos(theta)*sin(the ta)*uv)

tangential:
ut_rms=sqrt(cos(theta)*cos(theta)*SQR(uy_rms)+sin( theta)*sin(theta)*SQR(ux_rms)-2*cos(theta)*sin(theta)*uv)

July 7, 2016, 00:54	RMS Velocity coordinates transform?	#1
ray_lo New Member Ray Join Date: Oct 2015 Posts: 4 Rep Power: 11	Dear all, I have the RMS fluctuating velocities in Cartesian coordinate taken from a FLUENT LES simulation. But I now need to check the the RMS fluctuating velocities in cylindrical coordinate. Do anybody know how to transform RMS fluctuating velocities from Cartesian to cylindrical? Many thanks Ray

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July 9, 2016, 06:08		#2
ray_lo New Member Ray Join Date: Oct 2015 Posts: 4 Rep Power: 11	figure it out. actually quite easy ~_~ . I will put the answer here just for people who may need a quick answer of it. radial: ur_rms=sqrt(cos(theta)cos(theta)SQR(ux_rms)+sin( theta)sin(theta)SQR(uy_rms)+2cos(theta)sin(the ta)uv) tangential: ut_rms=sqrt(cos(theta)cos(theta)SQR(uy_rms)+sin( theta)sin(theta)SQR(ux_rms)-2cos(theta)sin(theta)uv)