Cylindrical cordinate system

hamoudi · July 21, 2009, 11:51

Hi Everybody,

I have 2D simulation i build my geometry and my Mesh in ICEM-CFD
then I export them to Star-cd, all thing is well in the same coordinate system cartesian to cartesian coordinate system.

But when i build my geometry and do my Mesh (ICEM-CFD) in cylindrical coordinate system in (r,theta,z)
then i have my geometry in (y,z) plane, so for the velocities
the radial velocity
U(r) is in -------- y direction
and U (theta) tangential velocity is in --------x direction
and U(z) is in ------------------------------- z direction

----------------------------------------------------------------
after that i export my Mesh to Star-CD
in boundary condition at the inlet part i change the coordinate system
from cartesian to cylindrical from number 1 to number 2
from ( x,y,z) to (r,theta,z)
then Star-CD consider that
the radial velocity U(r) is --------------------- in x direction
U (theta) is ----------------in y direction
U(z) is ---------------------in z direction

-------------------------------------------------------------------
so you can observe that there is a confusion in the axis from the initial case I try to do changement of the velocities to the axis
I put U(r) in y direction and U (theta) in x direction then my simulation did not convergt i have got a bad convergence
----------------------------------------------------------------------
Thank you very much i am in waiting for your suggestion

hamoudi · July 23, 2009, 07:38

Hi Everybody,

I have a problem,I have 2D simulation i build my geometry and my Mesh in ICEM-CFD, then I export them to Star-cd, all thing is well in the same coordinate system cartesian to cartesian coordinate system.

But when i build my geometry and do my Mesh (ICEM-CFD) in cylindrical coordinate system in (r,theta,z)
then i have my geometry in (y,z) plane, so for the velocities
the radial velocity
U(r) is in -------- y direction
and U (theta) tangential velocity is in --------x direction
and U(z) is in ------------------------------- z direction

----------------------------------------------------------------
after that i export my Mesh to Star-CD
in boundary condition at the inlet part i change the coordinate system
from cartesian to cylindrical from number 1 to number 2
from ( x,y,z) to (r,theta,z)
then Star-CD consider that
the radial velocity U(r) is --------------------- in x direction
U (theta) is ----------------in y direction
U(z) is ---------------------in z direction

-------------------------------------------------------------------
so you can observe that there is a confusion in the axis from the initial case I try to do changement of the velocities to the axis
I put U(r) in y direction and U (theta) in x direction then my simulation did not convergt i have got a bad convergence
----------------------------------------------------------------------
I am in waiting for your suggestion

Thank you very much for you

Pauli · July 24, 2009, 12:00

Their is no point is posting your question twice. (If I'm not going to respond to the first one, the second won't help.)

When working in cylindrical coordinates, U(r) must be in the x direction. So it sounds like you need to reorient your mesh. You can use the vtra or vgen commands to reorient your mesh. Enter help, vtra or help, vgen to get the details.

July 21, 2009, 11:51	Cylindrical cordinate system	#1
hamoudi Member Hamoudi djamel Join Date: Apr 2009 Posts: 50 Rep Power: 17	Hi Everybody, I have 2D simulation i build my geometry and my Mesh in ICEM-CFD then I export them to Star-cd, all thing is well in the same coordinate system cartesian to cartesian coordinate system. But when i build my geometry and do my Mesh (ICEM-CFD) in cylindrical coordinate system in (r,theta,z) then i have my geometry in (y,z) plane, so for the velocities the radial velocity U(r) is in -------- y direction and U (theta) tangential velocity is in --------x direction and U(z) is in ------------------------------- z direction ---------------------------------------------------------------- after that i export my Mesh to Star-CD in boundary condition at the inlet part i change the coordinate system from cartesian to cylindrical from number 1 to number 2 from ( x,y,z) to (r,theta,z) then Star-CD consider that the radial velocity U(r) is --------------------- in x direction U (theta) is ----------------in y direction U(z) is ---------------------in z direction ------------------------------------------------------------------- so you can observe that there is a confusion in the axis from the initial case I try to do changement of the velocities to the axis I put U(r) in y direction and U (theta) in x direction then my simulation did not convergt i have got a bad convergence ---------------------------------------------------------------------- Thank you very much i am in waiting for your suggestion

July 23, 2009, 07:38	Cylindrical Coordinate	#2
hamoudi Member Hamoudi djamel Join Date: Apr 2009 Posts: 50 Rep Power: 17	Hi Everybody, I have a problem,I have 2D simulation i build my geometry and my Mesh in ICEM-CFD, then I export them to Star-cd, all thing is well in the same coordinate system cartesian to cartesian coordinate system. But when i build my geometry and do my Mesh (ICEM-CFD) in cylindrical coordinate system in (r,theta,z) then i have my geometry in (y,z) plane, so for the velocities the radial velocity U(r) is in -------- y direction and U (theta) tangential velocity is in --------x direction and U(z) is in ------------------------------- z direction ---------------------------------------------------------------- after that i export my Mesh to Star-CD in boundary condition at the inlet part i change the coordinate system from cartesian to cylindrical from number 1 to number 2 from ( x,y,z) to (r,theta,z) then Star-CD consider that the radial velocity U(r) is --------------------- in x direction U (theta) is ----------------in y direction U(z) is ---------------------in z direction ------------------------------------------------------------------- so you can observe that there is a confusion in the axis from the initial case I try to do changement of the velocities to the axis I put U(r) in y direction and U (theta) in x direction then my simulation did not convergt i have got a bad convergence ---------------------------------------------------------------------- I am in waiting for your suggestion Thank you very much for you

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July 24, 2009, 12:00		#3
Pauli Senior Member Pauli Join Date: Mar 2009 Posts: 189 Rep Power: 17	Their is no point is posting your question twice. (If I'm not going to respond to the first one, the second won't help.) When working in cylindrical coordinates, U(r) must be in the x direction. So it sounds like you need to reorient your mesh. You can use the vtra or vgen commands to reorient your mesh. Enter help, vtra or help, vgen to get the details.