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December 31, 2013, 12:05 
LES inflow Generator Rostock

#1 
Senior Member
Bobi
Join Date: Oct 2012
Location: Chicago, Illinois
Posts: 372
Rep Power: 7 
Dear Foamers
I am searching for inflow generator of Rostock for LES applying on O.F. 2.2.x. It seems that the old links are failed. Does anybody has an active link? Regards Bobi 

January 1, 2014, 09:04 

#2 
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Hannes Kröger
Join Date: Mar 2009
Location: Rostock, Germany
Posts: 96
Rep Power: 10 
Hello Bobi,
Have a look at this link: http://www.lemos.unirostock.de/downloads/cfd/ There are the LEMOSextensions which contain the inflow generator. Regards, Hannes 

January 1, 2014, 12:57 

#3 
Senior Member
Bobi
Join Date: Oct 2012
Location: Chicago, Illinois
Posts: 372
Rep Power: 7 
Dear Dr. Kroger
Many thanks for your valuable link. I hope that installing the mentioned valuable tools be straightforward. Best Regards Bobi 

January 16, 2014, 21:51 

#4 
Member
Fluid Dynamics
Join Date: Mar 2013
Posts: 41
Rep Power: 5 
Dear Dr. Kroger,
One small question  Can this LES inflow BC be used for compressible (high speed flows) cases as well. As far as I can understand  this BC requires U,L and R from a precursor simulation (could be RANS) to generate vortons (synthetic turbulence). But in high speed flows we will also have Temperature fluctuations. What is your take on that? Maybe I can accommodate that using a fixed TotalTemperature BC, which will pick up velocity fluctuations to give me fluctuations in T static. Regarding Static pressure  need to think about it. I have seen this BC being applied to combustion problems but there all the action happens close to the flame and the inlet is in a place where things are incompressible. Maybe thats not the case. Any comments about all this? 

January 17, 2014, 04:12 

#5 
Member
Hannes Kröger
Join Date: Mar 2009
Location: Rostock, Germany
Posts: 96
Rep Power: 10 
Dear cfd.with.openfoam,
the inflow generator does not require a precursor simulation in general. Of course you need to have the distribution of L and R and the mean velocity from somewhere. But that doesn't need to be from a simulation, it could also be e.g. from a generic pipe or channel flow. You can even apply uniform values, if that makes any sense in your case. The inflow generator has been developed for incompressible flows so far and deals only with the problem of generating a turbulent velocity field, not the associated pressure or velocity fluctuations. So, as you already recognized: you can apply it, if you have a subsonic inflow in a compressible simulation. For really compressible turbulence, the method needs an extension. Regards, Hannes 

April 14, 2014, 05:08 

#6 
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Paul Lynch
Join Date: Aug 2013
Posts: 3
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Hi Hannes
Do you have any examples of specifying a nonuniform L and R field? I'm interested in modelling atmospheric boundary layer profiles, for which I could specify a function that approximates the integral length scale and turbulence intensity with height. Could this be done with groovyBC or similar? Regards, Paul 

June 13, 2015, 14:37 

#7  
Senior Member
Ehsan Asgari
Join Date: Apr 2010
Posts: 304
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Quote:
Regards 

November 4, 2015, 16:29 

#8  
New Member
Ali
Join Date: Apr 2010
Location: Greenville, South Carolina, USA
Posts: 10
Rep Power: 8 
Quote:
Have you found any work around having an atmospheric boundary layer inflow for LES while using LEMOS as synthetic turbulence generator? Thanks! 

November 4, 2015, 19:42 

#9  
Senior Member
Ehsan Asgari
Join Date: Apr 2010
Posts: 304
Rep Power: 9 
Quote:
I could successfully implement groovy bc to get a powerlaw velocity profile to use as the refField in LeMOS inflow generator. Bests 

November 5, 2015, 05:08 

#10 
New Member
Paul Lynch
Join Date: Aug 2013
Posts: 3
Rep Power: 5 
My approach is to run a preliminary simulation for a single iteration with the inlet boundary in one of the scalar variables set to a simple groovyBC function to output the cell vertical coordinates (i.e. pos().z). I then input those coordinates into fitting functions for the velocity, turbulence length scale etc. to create lists for the inflow boundary condition  you could do this in a spreadsheet, or script it, depending on what you're happiest with.


February 10, 2016, 11:44 
Is the LEMOS inflow generator divergencefree?

#11 
New Member
Join Date: Nov 2014
Posts: 3
Rep Power: 4 
Hi everybody,
I would like to understand more about the turbulence generation at the inflow boundary with this method. In particular, I am a bit confused about the difference between the Turbulent Spots and Vortons: what is the difference? In addition, which is used in the version 2.3.x and, in the end, is the available method divergencefree? Thank you very much in advance for your possible answers. 

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