Question about mass flow export in element face

Jaemin Park · September 22, 2011, 04:18

Glad to see you guys, I'm turbine engineer and I have some questions about ANSYS CFX-post.

I want to export the mass flow rate from every mesh element's faces. In my case, all mesh is hexahedral so there are 6 faces in each elements. In the export tools in CFX-post, I can export the information at the node only, not at the control volume or element volume or element faces.
Is it possible? If it is possible, how can I export that informations?

Thank you for read. Have a nice day!

ghorrocks · September 22, 2011, 06:11

I don't think you can export data from anything except the nodes. The nodes are the only location where the variables are stored.

You might be able to get something out of the export options in the solver manager (under tools), but no guarantees.

michael_owen · September 22, 2011, 10:09

The data at the nodes ARE the data at the control volumess; that's what a node is, the center of the control volume, and the data stored there are averages over the control volume.

Jaemin Park · September 22, 2011, 19:44

Thank you ghorrocks, I will try to export from the solver CGNS options.

Jaemin Park · September 22, 2011, 19:46

Thank you for reply owen.
I know the node value is the average value for control volume.
But I want to know the inlet volume flow rate in each control volume, and that means I have to export the mass flow from every faces in each control volume.
node is just a point so mass flow value is 'null'.

ghorrocks · September 23, 2011, 07:36

I can't see a way of doing this. Why do you want to export the face mass fluxes?

Jaemin Park · September 24, 2011, 05:01

Thank you Glenn,

In my work, I have to devide the entropy generation for each flow region. I can't use the absolute entropy value of CFD results, because I can't get the entropy generation rate from absolute value. So I just calculate the entropy generation rate from turbulent dissipation epsilon. And then, I have to know the delta t(time) of each cell for integrating entropy generation. Delta t might be the ratio of each element's volume and volume flow rate ( (m3)/(m3/s) ).

I try to export the cgns type results from solver, but I also can't find the way to do.

ghorrocks · September 24, 2011, 06:24

I suspect you can do this inside CFD-Post with no need to export anything. But I do not know the detail of what you are calculating so cannot be sure.

You do the CGNS export in the solver manager, under tools/export.

September 22, 2011, 04:18	Question about mass flow export in element face	#1
Jaemin Park New Member Jaemin Park Join Date: Sep 2011 Posts: 4 Rep Power: 14	Glad to see you guys, I'm turbine engineer and I have some questions about ANSYS CFX-post. I want to export the mass flow rate from every mesh element's faces. In my case, all mesh is hexahedral so there are 6 faces in each elements. In the export tools in CFX-post, I can export the information at the node only, not at the control volume or element volume or element faces. Is it possible? If it is possible, how can I export that informations? Thank you for read. Have a nice day!

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September 22, 2011, 06:11		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	I don't think you can export data from anything except the nodes. The nodes are the only location where the variables are stored. You might be able to get something out of the export options in the solver manager (under tools), but no guarantees.

September 22, 2011, 10:09		#3
michael_owen Senior Member Michael P. Owen Join Date: Mar 2009 Posts: 196 Rep Power: 17	The data at the nodes ARE the data at the control volumess; that's what a node is, the center of the control volume, and the data stored there are averages over the control volume.

September 22, 2011, 19:44		#4
Jaemin Park New Member Jaemin Park Join Date: Sep 2011 Posts: 4 Rep Power: 14	Thank you ghorrocks, I will try to export from the solver CGNS options.

September 22, 2011, 19:46		#5
Jaemin Park New Member Jaemin Park Join Date: Sep 2011 Posts: 4 Rep Power: 14	Thank you for reply owen. I know the node value is the average value for control volume. But I want to know the inlet volume flow rate in each control volume, and that means I have to export the mass flow from every faces in each control volume. node is just a point so mass flow value is 'null'.

September 23, 2011, 07:36		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	I can't see a way of doing this. Why do you want to export the face mass fluxes?

September 24, 2011, 05:01		#7
Jaemin Park New Member Jaemin Park Join Date: Sep 2011 Posts: 4 Rep Power: 14	Thank you Glenn, In my work, I have to devide the entropy generation for each flow region. I can't use the absolute entropy value of CFD results, because I can't get the entropy generation rate from absolute value. So I just calculate the entropy generation rate from turbulent dissipation epsilon. And then, I have to know the delta t(time) of each cell for integrating entropy generation. Delta t might be the ratio of each element's volume and volume flow rate ( (m3)/(m3/s) ). I try to export the cgns type results from solver, but I also can't find the way to do.

September 24, 2011, 06:24		#8
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	I suspect you can do this inside CFD-Post with no need to export anything. But I do not know the detail of what you are calculating so cannot be sure. You do the CGNS export in the solver manager, under tools/export.