# How can i get velocity value on fluent ?

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 April 8, 2015, 18:33 How can i get velocity value on fluent ? #1 Member   Join Date: Apr 2015 Posts: 41 Rep Power: 9 How can i get velocity values on a flat plate ? Example; i want to calculate velocity value at L/2 location of a flat plate ?

 April 8, 2015, 19:44 #2 Senior Member   Join Date: Mar 2015 Posts: 892 Rep Power: 16 Within Fluent: Display > Plots... Otherwise, using CFD-Post might be easier if you have the license. Create a point (2-D case) or a line (3-D case) location at x=L/2 and create a chart of the velocity in this new location. Falcon35 likes this.

April 9, 2015, 04:24
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 Originally Posted by `e` Within Fluent: Display > Plots... Otherwise, using CFD-Post might be easier if you have the license. Create a point (2-D case) or a line (3-D case) location at x=L/2 and create a chart of the velocity in this new location.
How can i do it by using line/rake ?

 April 9, 2015, 04:29 #4 Senior Member   Cees Haringa Join Date: May 2013 Location: Delft Posts: 607 Rep Power: 0 go to the plot menu as 'e' mentioned. There, you will need to select a location for the plot; you can make a line/rake and select it there. Then set the appropriate x and y values (you can use curve length for the x-axis if you want to measure along the line), and you're good to go! If you want to export the plot, tick 'write to file'. The values will be printed in a text file, which you can load in excel, matlab or another program of choice to make a nicer graph that FLUENT can do. Falcon35 likes this.

April 9, 2015, 04:39
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 Originally Posted by CeesH go to the plot menu as 'e' mentioned. There, you will need to select a location for the plot; you can make a line/rake and select it there. Then set the appropriate x and y values (you can use curve length for the x-axis if you want to measure along the line), and you're good to go! If you want to export the plot, tick 'write to file'. The values will be printed in a text file, which you can load in excel, matlab or another program of choice to make a nicer graph that FLUENT can do.
Bro thank you but can you describe it like this, surface> line/rake , create a vertical line at x = L/2 , then do it to calculate horizontal velocity value at that location. I need this please?

 April 9, 2015, 04:45 #6 Senior Member   Cees Haringa Join Date: May 2013 Location: Delft Posts: 607 Rep Power: 0 Go to surface > line/rake > set the coordinates of the start and end point of your line, give the line a name and create it. Now go to plot > x-y plot. Under surfaces (bottom right), select the line you created. As y-axis function, set the velocity (or other parameter you want to check). For x-axis function, choose curve-length Falcon35 likes this.

April 9, 2015, 04:50
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 Originally Posted by CeesH Go to surface > line/rake > set the coordinates of the start and end point of your line, give the line a name and create it. Now go to plot > x-y plot. Under surfaces (bottom right), select the line you created. As y-axis function, set the velocity (or other parameter you want to check). For x-axis function, choose curve-length
Why y-axis set to velocity? I want to calculate horizontal velocity at L/2 and calculate boundary layer thickness

 April 9, 2015, 05:04 #8 Member   Join Date: Apr 2015 Posts: 41 Rep Power: 9 Please help me ...

 April 9, 2015, 05:09 #9 Senior Member   Cees Haringa Join Date: May 2013 Location: Delft Posts: 607 Rep Power: 0 You can plot the horizontal velocity at the vertical line you made. In that case, as a y-axis function, set x-velocity. (you can also swap the axis if you want; in that case, set the y-axis function as mesh > y, and the x-axis function as x-velocity)

April 9, 2015, 05:15
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 Originally Posted by CeesH You can plot the horizontal velocity at the vertical line you made. In that case, as a y-axis function, set x-velocity. (you can also swap the axis if you want; in that case, set the y-axis function as mesh > y, and the x-axis function as x-velocity)
will i read L/2 velocity in writed file ?

 April 9, 2015, 05:26 #11 Senior Member   Cees Haringa Join Date: May 2013 Location: Delft Posts: 607 Rep Power: 0 Only if there is a nodal point at L/2. Otherwise you will have to interpolate between the closest points, or take the closes node value to L/2. If you have the CFD-post license, as 'e' mentioned, it may be more convenient to do it in there. In CFD-post you have an automated interpolation option as well. Falcon35 likes this.

April 9, 2015, 05:43
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 Originally Posted by CeesH Only if there is a nodal point at L/2. Otherwise you will have to interpolate between the closest points, or take the closes node value to L/2. If you have the CFD-post license, as 'e' mentioned, it may be more convenient to do it in there. In CFD-post you have an automated interpolation option as well.
Then how can i obtain boundary layer thickness change due to location L/4 , L/2 ,3L/4 and L ?

 April 9, 2015, 05:50 #13 Senior Member   Cees Haringa Join Date: May 2013 Location: Delft Posts: 607 Rep Power: 0 Ok, now I have a better idea of what you want - that was unclear to me first. If you make a vertical line at x = L/2, yes, the values of x-velocity at L/2 will be exactly given, over the y-position in the boundary layer. If you want to have the values at other values of x, also set up a line at those positions, and repeat the plotting there. Make a plot for x-velocity vs y-position at every x you want. Falcon35 likes this.

April 9, 2015, 06:02
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 Originally Posted by CeesH Ok, now I have a better idea of what you want - that was unclear to me first. If you make a vertical line at x = L/2, yes, the values of x-velocity at L/2 will be exactly given, over the y-position in the boundary layer. If you want to have the values at other values of x, also set up a line at those positions, and repeat the plotting there. Make a plot for x-velocity vs y-position at every x you want.
Bro, can you help me by teamviewer later to obtain boundary layer thickness change due to location of L?

 April 9, 2015, 06:41 #15 Senior Member   Cees Haringa Join Date: May 2013 Location: Delft Posts: 607 Rep Power: 0 Sorry, don't have time for that. But I think if you follow the steps, everything should work out fine.

April 9, 2015, 07:35
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 Originally Posted by CeesH Sorry, don't have time for that. But I think if you follow the steps, everything should work out fine.
Thank you then