Tecplot 360 2013 Non Zero Velocity at the Wall with FLUENT data

LeDude · July 24, 2014, 17:14

Hi Tecplot users!

This is my first post

Recently I decided to try and use Tecplot for post-processing Fluent data instead of the CFD Post Processor from Ansys.

However, when I load my Fluent .cas and .dat files using the Fluent data loader I get a non zero velocity at the walls of my domain. This is of course not physical due to the no slip condition. My guess is that Tecplot uses the data at the grid node adjacent to the wall.

If I plot the velocity at the wall using CFD Post from I get a zero velocity at the wall.

Has anyone else experienced this, and know of any solutions?

Kind Regards

scott_rumage · July 25, 2014, 19:39

This is a known issue as Fluent data files store their information at the cell centers, and Tecplot 360 plots from nodal values. Tecplot 360 reads Fluent's cell-centered information and extrapolates to the nodal locations. This extrapolation process yields a non-zero velocity at a surface for Fluent data.

One can eliminate this issue if the export from Fluent is specified as nodal (not cell-centered). The specification of cell or nodal values can be made in Fluent’s CGNS data export. Information stored at the nodes will show will show a zero velocity at the wall in Tecplot 360.

Scott

LeDude · July 26, 2014, 14:49

Hi Scott,

Thank you for the answer.

I tried doing as you suggest, but when I import the CGNS file with the node centered data all variables have the value zero in the entire domain.

I also tried using "Specify Equation" in Tecplot to assign zero velocity to all the velocity components at the wall. Now if I make a contour plot of the velocity magnitue on the wall I get a value of zero everywhere.

However, if I make a vector plot of a slice plane, Tecplot still draw velocity vectors at the wall nodes.

Is there any way to circumvent this? I have attached an image to illustrate the situation.

Regards

scott_rumage · July 28, 2014, 19:11

Sorry that I wasn't of much help. I don't have any suggestions other than to double check that the CGNS export file from Fluent was specified as having the data at the nodes.

When I did this type of export, I did have zero velocity at the wall and the remaining domain data appear as expected.

Scott

July 24, 2014, 17:14	Tecplot 360 2013 Non Zero Velocity at the Wall with FLUENT data	#1
LeDude New Member Join Date: Oct 2013 Posts: 2 Rep Power: 0	Hi Tecplot users! This is my first post Recently I decided to try and use Tecplot for post-processing Fluent data instead of the CFD Post Processor from Ansys. However, when I load my Fluent .cas and .dat files using the Fluent data loader I get a non zero velocity at the walls of my domain. This is of course not physical due to the no slip condition. My guess is that Tecplot uses the data at the grid node adjacent to the wall. If I plot the velocity at the wall using CFD Post from I get a zero velocity at the wall. Has anyone else experienced this, and know of any solutions? Kind Regards

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July 25, 2014, 19:39		#2
scott_rumage Senior Member Scott Rumage Join Date: May 2009 Location: Seattle, WA Posts: 152 Rep Power: 17	This is a known issue as Fluent data files store their information at the cell centers, and Tecplot 360 plots from nodal values. Tecplot 360 reads Fluent's cell-centered information and extrapolates to the nodal locations. This extrapolation process yields a non-zero velocity at a surface for Fluent data. One can eliminate this issue if the export from Fluent is specified as nodal (not cell-centered). The specification of cell or nodal values can be made in Fluent’s CGNS data export. Information stored at the nodes will show will show a zero velocity at the wall in Tecplot 360. Scott

July 28, 2014, 19:11		#4
scott_rumage Senior Member Scott Rumage Join Date: May 2009 Location: Seattle, WA Posts: 152 Rep Power: 17	Sorry that I wasn't of much help. I don't have any suggestions other than to double check that the CGNS export file from Fluent was specified as having the data at the nodes. When I did this type of export, I did have zero velocity at the wall and the remaining domain data appear as expected. Scott