LES inflow Generator Rostock

babakflame · December 31, 2013, 11:05

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

hannes · January 1, 2014, 08:04

Hello Bobi,

Have a look at this link:

http://www.lemos.uni-rostock.de/downloads/cfd/

There are the LEMOS-extensions which contain the inflow generator.

Regards, Hannes

babakflame · January 1, 2014, 11:57

Dear Dr. Kroger

Many thanks for your valuable link. I hope that installing the mentioned valuable tools be straightforward.

Best Regards
Bobi

cfd.with.openfoam · January 16, 2014, 20:51

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?

hannes · January 17, 2014, 03:12

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

pmlynch · April 14, 2014, 05:08

Hi Hannes

Do you have any examples of specifying a non-uniform 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

syavash · June 13, 2015, 14:37

Quote:

Originally Posted by pmlynch

Hi Hannes

Do you have any examples of specifying a non-uniform 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

Dear Paul, I am also interested in something similar. I need to specify a boundary layer velocity profile in turbulence inflow generator. Could you manage to find a way to specify non-uniform distribution?!
Regards

gentela · November 4, 2015, 15:29

Quote:

Originally Posted by syavash

Dear Paul, I am also interested in something similar. I need to specify a boundary layer velocity profile in turbulence inflow generator. Could you manage to find a way to specify non-uniform distribution?!
Regards

Dear Syavash,

Have you found any work around having an atmospheric boundary layer inflow for LES while using LEMOS as synthetic turbulence generator?

Thanks!

syavash · November 4, 2015, 18:42

Quote:

Originally Posted by gentela

Dear Syavash,

Have you found any work around having an atmospheric boundary layer inflow for LES while using LEMOS as synthetic turbulence generator?

Thanks!

Hi,

I could successfully implement groovy bc to get a power-law velocity profile to use as the refField in LeMOS inflow generator.

Bests

pmlynch · November 5, 2015, 04:08

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.

azzurroblake · February 10, 2016, 10:44

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 divergence-free?

Thank you very much in advance for your possible answers.

December 31, 2013, 11:05	LES inflow Generator Rostock	#1
babakflame Senior Member Bobby Join Date: Oct 2012 Location: Michigan Posts: 454 Rep Power: 15	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, 08:04		#2
hannes Senior Member Hannes Kröger Join Date: Mar 2009 Location: Rostock, Germany Posts: 123 Rep Power: 18	Hello Bobi, Have a look at this link: http://www.lemos.uni-rostock.de/downloads/cfd/ There are the LEMOS-extensions which contain the inflow generator. Regards, Hannes songwukong, babakflame and chengyu like this.

January 17, 2014, 03:12		#5
hannes Senior Member Hannes Kröger Join Date: Mar 2009 Location: Rostock, Germany Posts: 123 Rep Power: 18	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 songwukong and babakflame like this.

February 10, 2016, 10:44	Is the LEMOS inflow generator divergence-free?	#11
azzurroblake New Member Join Date: Nov 2014 Posts: 3 Rep Power: 11	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 divergence-free? Thank you very much in advance for your possible answers.

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January 1, 2014, 11:57		#3
babakflame Senior Member Bobby Join Date: Oct 2012 Location: Michigan Posts: 454 Rep Power: 15	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, 20:51		#4
cfd.with.openfoam Member Fluid Dynamics Join Date: Mar 2013 Posts: 41 Rep Power: 13	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?

April 14, 2014, 05:08		#6
pmlynch New Member Paul Lynch Join Date: Aug 2013 Posts: 5 Rep Power: 12	Hi Hannes Do you have any examples of specifying a non-uniform 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

November 5, 2015, 04:08		#10
pmlynch New Member Paul Lynch Join Date: Aug 2013 Posts: 5 Rep Power: 12	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.