cylindrical mesh

m.malysza · October 10, 2011, 07:58

Why when using cylindrical mesh there is a plane 1 and 2, so the contact is from 0 - 360 degrees. I have uploaded two pictures demonstrating the problem. And my Q is how to eliminate this line.
1.
http://imageshack.us/photo/my-images/255/27918353.jpg/
2.
http://imageshack.us/photo/my-images/607/33350229.jpg/
BSR

master77 · November 21, 2011, 07:46

I have the same problem. The grid seems to be not perfectly closed on 0-360°. The computation is affected by giving results not accectable in my case. Does anyone know how to guarantee a perfect closure of the cylindrical mesh? Thx Giacomo

JBurnham · November 30, 2011, 14:44

See the question and answer about periodic boundaries.

saeedtk · September 11, 2013, 04:07

is this problem solved? plz help

JBurnham · September 11, 2013, 12:45

There's not a problem. In cylindrical coords, like in Cartesian, there are always six boundary conditions per mesh block. The boundaries don't close up. Instead, you set the y-boundaries to 'periodic'. Whatever fluid, scalars, particles, etc. cross out of one y-boundary appear at the same elevation at the opposite boundary. This lets you make a quarter-model of a cylindrical tank without modeling the entire tank space, for instance. If you wrap the mesh 360 degrees around the axis, then you're modeling the whole tank, but you still use periodic boundaries to represent the connection between one end of the mesh and the other.

saeedtk · September 11, 2013, 13:15

thank friend for your response
im studying a hydrocyclone in which we have rotary flow, this method works there? and another thing , u mean in cylindrical coordination the Ymax and Ymin represent the two starting and ending surfaces of cylindrical mesh?

Regards

JBurnham · September 11, 2013, 16:08

Yes, the Pd-boundaries in y work for rotating flow, and have been used for cyclonic modeling with FLOW-3D. - Jeff

October 10, 2011, 07:58	cylindrical mesh	#1
m.malysza New Member Marcin Join Date: Sep 2010 Posts: 8 Rep Power: 16	Why when using cylindrical mesh there is a plane 1 and 2, so the contact is from 0 - 360 degrees. I have uploaded two pictures demonstrating the problem. And my Q is how to eliminate this line. 1. http://imageshack.us/photo/my-images/255/27918353.jpg/ 2. http://imageshack.us/photo/my-images/607/33350229.jpg/ BSR

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November 21, 2011, 07:46		#2
master77 New Member Giacomo Vi Join Date: Nov 2011 Posts: 3 Rep Power: 15	I have the same problem. The grid seems to be not perfectly closed on 0-360°. The computation is affected by giving results not accectable in my case. Does anyone know how to guarantee a perfect closure of the cylindrical mesh? Thx Giacomo

November 30, 2011, 14:44		#3
JBurnham Senior Member Jeff Burnham Join Date: Apr 2010 Posts: 204 Rep Power: 17	See the question and answer about periodic boundaries.

September 11, 2013, 04:07		#4
saeedtk New Member Join Date: May 2013 Posts: 6 Rep Power: 13	is this problem solved? plz help

September 11, 2013, 12:45		#5
JBurnham Senior Member Jeff Burnham Join Date: Apr 2010 Posts: 204 Rep Power: 17	There's not a problem. In cylindrical coords, like in Cartesian, there are always six boundary conditions per mesh block. The boundaries don't close up. Instead, you set the y-boundaries to 'periodic'. Whatever fluid, scalars, particles, etc. cross out of one y-boundary appear at the same elevation at the opposite boundary. This lets you make a quarter-model of a cylindrical tank without modeling the entire tank space, for instance. If you wrap the mesh 360 degrees around the axis, then you're modeling the whole tank, but you still use periodic boundaries to represent the connection between one end of the mesh and the other.

September 11, 2013, 13:15		#6
saeedtk New Member Join Date: May 2013 Posts: 6 Rep Power: 13	thank friend for your response im studying a hydrocyclone in which we have rotary flow, this method works there? and another thing , u mean in cylindrical coordination the Ymax and Ymin represent the two starting and ending surfaces of cylindrical mesh? Regards

September 11, 2013, 16:08		#7
JBurnham Senior Member Jeff Burnham Join Date: Apr 2010 Posts: 204 Rep Power: 17	Yes, the Pd-boundaries in y work for rotating flow, and have been used for cyclonic modeling with FLOW-3D. - Jeff