# calculating mean streamwise velocity in LES

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 August 10, 2010, 18:16 calculating mean streamwise velocity in LES #1 Senior Member     Join Date: Jan 2010 Posts: 347 Blog Entries: 2 Rep Power: 10 Dear Foamers i run a backward facing step case with pisoFoam LES. Now, i want plot mean stream wise velocity diagram over a specific line. i have values of stream wise velocity in all time steps but i don't know how can i reach a diagram which show mean stream wise velocity in last time steps. . please tell me its scheme in paraView or Tecplot. (i know LES doesn't lead to steady state and doesn't have periodic manner but i saw different works which displayed mean stream wise velocity of BFS with LES.) Best,

 August 10, 2010, 20:13 #2 Member   Simon Lapointe Join Date: May 2009 Location: Québec, Qc, Canada Posts: 33 Rep Power: 10 To obtain mean velocity (or other variables), you can use the fieldAverage function object during your simulation. This will calculate the average at each time step, and create mean fields. For example, to average U and p just add the following to your controlDict : functions ( fieldAverage1 { // Type of functionObject type fieldAverage; // Where to load it from (if not already in solver) functionObjectLibs ("libfieldAverage.so"); // Fields to be averaged - runTime modifiable fields ( U { mean on; prime2Mean on; base time; } p { mean on; prime2Mean on; base time; } ); } );

 August 11, 2010, 04:31 #3 Senior Member     Join Date: Jan 2010 Posts: 347 Blog Entries: 2 Rep Power: 10 Thanks Simon, I don't want mean velocity in each time step. i want mean velocity in several time steps in end of simulation times to display a diagram of mean velocity over a line. i don't know how many time step should be considered to show MEAN manner and how to calculate this value. Best,

 August 12, 2010, 16:07 #4 Senior Member     Join Date: Jan 2010 Posts: 347 Blog Entries: 2 Rep Power: 10 Any idea ?

September 6, 2010, 11:38
#5
Member

edison
Join Date: May 2009
Location: Australia
Posts: 35
Rep Power: 10
Quote:
 Originally Posted by maysmech Any idea ?
I'm having the same problem. And I think the time average in the last time step is the result you are looking for. Just follow the link below and see how things go.

http://www.cfd-online.com/Forums/ope...tatistics.html

 Tags les, paraview, stream wise velocity

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