# Non-isothermal incompressible LES in OpenFOAM

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 January 14, 2014, 10:22 Non-isothermal incompressible LES in OpenFOAM #1 New Member   Sagnik Join Date: Oct 2012 Posts: 27 Rep Power: 9 Hi, I was wondering which solver should we use to simulate a 'Non-isothermal incompressible LES in OpenFOAM' without the boussinesq approximation. I understand there is a well laid out procedure for flows with 'boussinesq approximation': http://openfoamwiki.net/index.php/Bu...sinesqPisoFoam We would like to use temperature dependent fluid properties for the LES simulation (ideal gas for density of good enough). Any information would be of great help. Thanks for all the help. Sagnik

January 14, 2014, 11:34
#2
Senior Member

Chris Sideroff
Join Date: Mar 2009
Location: Ottawa, ON, CAN
Posts: 415
Rep Power: 18
If you want temperature dependent fluid properties through ideal gas law, it will no longer be incompressible. The point of the Boussinesq approach is to avoid variable density (and the compressible formulation) and instead "model" density changes through a body force term dependent on temperature.

The rule of thumb for Boussinesq validity is

Your alternative is to explore the buoyantPimpleFoam solver which has variable density but as I mentioned will be compressible.

Quote:
 Originally Posted by sagnikmazumdar Hi, I was wondering which solver should we use to simulate a 'Non-isothermal incompressible LES in OpenFOAM' without the boussinesq approximation. I understand there is a well laid out procedure for flows with 'boussinesq approximation': http://openfoamwiki.net/index.php/Bu...sinesqPisoFoam We would like to use temperature dependent fluid properties for the LES simulation (ideal gas for density of good enough). Any information would be of great help. Thanks for all the help. Sagnik

 January 14, 2014, 12:20 #3 New Member   Sagnik Join Date: Oct 2012 Posts: 27 Rep Power: 9 Yes, very true. I understand that you are suggesting 'buoyantPimpleFoam' solver. Would it be possible for you to suggest us a good reference work with OpenFOAM in this regard ! Thanks for all the help and inputs. Sagnik

 January 14, 2014, 13:28 #4 Senior Member   Chris Sideroff Join Date: Mar 2009 Location: Ottawa, ON, CAN Posts: 415 Rep Power: 18 If you check out the buoyantPimpleFoam source you will see it's already capable of using LES. Switching between RAS and LES is handled in the constant/turbulenceProperties dictionary. Then add/modify an constant/LESProperties dictionary to define the LES model you want to use. Since it's compressible you may want to refer to one of the existing LES compressible tutorials for model and BC options. Good luck

 December 5, 2014, 02:14 #5 Member   Florian Ries Join Date: Feb 2014 Location: Darmstadt, Germany Posts: 88 Rep Power: 8 Hi all, just for better understanding: if the density is only a function of temperature and composition, then the flow is incompressible but the density can change!!!! (with temperature and composition). In an compressible flow, the denisty is a function of pressure. If the Mach number is higer then lets say 0.3 , we have to care about the pressure. The most people think that incompressible is if density do not change. This is wrong! This kind of flow is constant density flow. In my opinion it is very confusing in OpenFoam, that some solvers are called compressible and incompressible. For example buoyantPimpleFoam can be used for compressible and incompressible flow. It depends on which equation of state you use in thermophysicalProperties dictionary. If you choose: equationOfState incompressiblePerfectGas; then the flow is incompressible. If you choose: equationOfState perfectGas; then the flow is compressible. In both cases the density can change. kind regards Florian ykanani likes this.

 December 5, 2014, 02:19 #6 Member   Florian Ries Join Date: Feb 2014 Location: Darmstadt, Germany Posts: 88 Rep Power: 8 Hi drmarcoguevara, bouyantPimpleFoam and bouyantSimpleFoam should be able to handle non-isothermal incompressible flow. But I am very intrested in the code you mentioned. Could you please upload the code in the forum?? Then we can verificate the code. This should be helpfull for you as well. If this is impossible, could you please send me the code: ries@ekt.tu-darmstadt.de kind regards Florian

 March 9, 2016, 03:41 #7 New Member   Desanga Join Date: Dec 2013 Posts: 19 Rep Power: 8 hi drmarcoguevara, could you please share your code with us Thanks

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