# xPlus utility

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 August 18, 2015, 06:36 xPlus utility #1 Senior Member   Ehsan Asgari Join Date: Apr 2010 Posts: 304 Rep Power: 9 Dear Foamers, Is there any utility developed for calculating xPlus and zPlus in a LES simulation?! Thanks, Syavash

 August 18, 2015, 10:48 #2 Super Moderator   Bruno Santos Join Date: Mar 2009 Location: Lisbon, Portugal Posts: 9,747 Blog Entries: 39 Rep Power: 103 Quick question: Can you please provide more details on what are you talking about? In other words: What are "x+" and "z+"?

August 18, 2015, 14:01
#3
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Ehsan Asgari
Join Date: Apr 2010
Posts: 304
Rep Power: 9
Quote:
 Originally Posted by wyldckat Quick question: Can you please provide more details on what are you talking about? In other words: What are "x+" and "z+"?

Hi Bruno,

You make me ashamed of myself!!
By x+ I meant a cell streamwise grid spacing, non-dimensionalized by friction velocity and dynamic viscosity. Maybe I should have named it deltax+.
It is just like deltay+ except in spatial direction.
I need to evalute my grid spacings to compare with literature in terms of x+ and z+ distribution on the wall.

Syavash

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A good starting point may be yPlusLES utility, but I cannot manage to find how to consider streamwise grid spacing instead of wall normal spacing.

Last edited by wyldckat; August 18, 2015 at 14:20. Reason: merged posts that were a few minutes apart

 August 18, 2015, 14:28 #4 Super Moderator   Bruno Santos Join Date: Mar 2009 Location: Lisbon, Portugal Posts: 9,747 Blog Entries: 39 Rep Power: 103 Quick answer: Mmm... sorry, I was expecting something more related to LES modelling, perhaps something related to the filters or something like that... hence my question. The problem is that the "x" and "z" measurements can't be easily done generically: The "y" value is the distance of the centre of the face on the wall to the centre of the cell, which are both well defined. The remaining dimensions would possibly have to rely on the bounding box of the cell, i.e. to create the minimum and maximum measurements for all vertices of each cell, but in the coordinates of the flow. This to say that its probably why there is not yet such a utility that calculates this for OpenFOAM. Either way, you can draw some calculation ideas from the solver "applications/solvers/incompressible/boundaryFoam".

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