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June 22, 2020, 12:40 |
Natural convection boundary layer flow
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#1 |
Member
Alex
Join Date: May 2019
Posts: 36
Rep Power: 6 |
Hello everyone, I would like to simulate the boundary layer flow created by natural convection. My scope is to make a 2D simulation of a vertical hot wall using BuoyantBoussinesqPimplefoam. In my simulation I can never see the boundary layer, all the air in the domain is moving upwards, instead I would like to see only the air in the boundary layer moving upwards, and the rest should be at zero velocity. I attached the case folder in case you want to help me to address which my problem is. I think that the problem could be:
My main issue was to find the right BC for this problem, I litterally tried to guess, because I could not find anything helpful around. If any of you know how to set the BC for this kind of problem, it would be already a great help. |
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June 23, 2020, 04:31 |
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#2 |
Member
Alex
Join Date: May 2019
Posts: 36
Rep Power: 6 |
Here I post the BC settings, I am quite sure that the problem is here but I do not know where. The shape of the domain is a sort of square, up and down is an open face for output and input, on the left side is also open to simulate the atmosphere, on the center of the right side there is the hot wall, and above and below it there should still be atmosphere.
Code:
/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 5 | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class volScalarField; object p_rgh; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 2 -2 0 0 0 0]; internalField uniform 0; boundaryField { hotWall { type fixedFluxPressure; value uniform 1e5; } atmosphere { type zeroGradient; } inlet { type totalPressure; p0 uniform 0; } outlet { type totalPressure; p0 uniform 0; } //#includeEtc "caseDicts/setConstraintTypes" } // ************************************************************************* // Code:
/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 5 | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class volScalarField; object T; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 0 0 1 0 0 0]; internalField uniform 300; boundaryField { hotWall { type fixedValue; value uniform 301; } atmosphere { type fixedValue; value uniform 300; } inlet { type fixedValue; value uniform 300; } outlet { type fixedValue; value uniform 300; } // #includeEtc "caseDicts/setConstraintTypes" } // ************************************************************************* // Code:
/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 5 | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class volVectorField; object U; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 1 -1 0 0 0 0]; internalField uniform (0 0 0); boundaryField { hotWall { type fixedValue; value uniform (0 0 0); } atmosphere { type fixedValue; value uniform (0 0 0); } inlet { type zeroGradient; } outlet { type inletOutlet; value $internalField; inletValue uniform (0 0 0); } // #includeEtc "caseDicts/setConstraintTypes" } // ************************************************************************* // |
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July 1, 2020, 15:14 |
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#3 |
Senior Member
Agustín Villa
Join Date: Apr 2013
Location: Alcorcón
Posts: 313
Rep Power: 15 |
Hello Sedullo,
I have a bit of experience running this flow. I need some information
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July 2, 2020, 09:56 |
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#4 |
Member
Alex
Join Date: May 2019
Posts: 36
Rep Power: 6 |
Hello agustinvo,
Thenk you very much for the reply. My goal is to run a laminar flow, so I just set "laminar" in the turbulenceProperties and paid attention to keep the Grashof number in the laminar range. I attached the temperature field and the velocity vectors field. But I see two problems:
I made some changes in U, T and p_rgh Code:
/*--------------------------------*- C++ -*----------------------------------*\ ========= | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox \\ / O peration | Website: https://openfoam.org \\ / A nd | Version: 6 \\/ M anipulation | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class volScalarField; object T; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 0 0 1 0 0 0]; internalField uniform 300; boundaryField { hotWall { type fixedValue; value uniform 310; } atmosphere { type zeroGradient; } inlet { type fixedValue; value uniform 300; } outlet { type zeroGradient; } // #includeEtc "caseDicts/setConstraintTypes" } // ************************************************************************* // Code:
/*--------------------------------*- C++ -*----------------------------------*\ ========= | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox \\ / O peration | Website: https://openfoam.org \\ / A nd | Version: 6 \\/ M anipulation | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class volVectorField; object U; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 1 -1 0 0 0 0]; internalField uniform (0 0 0); boundaryField { hotWall { type noSlip; } atmosphere { type slip; } inlet { type outletInlet; outletValue uniform (0 0 0); value uniform (0 0 0); } outlet { type inletOutlet; inletValue uniform (0 0 0); value uniform (0 0 0); } // #includeEtc "caseDicts/setConstraintTypes" } // ************************************************************************* // Code:
/*--------------------------------*- C++ -*----------------------------------*\ ========= | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox \\ / O peration | Website: https://openfoam.org \\ / A nd | Version: 6 \\/ M anipulation | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class volScalarField; object p_rgh; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 2 -2 0 0 0 0]; internalField uniform 1e5; boundaryField { hotWall //type zeroGradient; // type fixedFluxPressure; // rho rhok; // value uniform 0; { type fixedFluxPressure; value uniform 1e5; } atmosphere { type fixedFluxPressure; value uniform 1e5; } inlet { type fixedFluxPressure; value uniform 1e5; } outlet { type totalPressure; p0 uniform 1e5; //value $internalField; } //#includeEtc "caseDicts/setConstraintTypes" } // ************************************************************************* // Code:
/*--------------------------------*- C++ -*----------------------------------*\ ========= | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox \\ / O peration | Website: https://openfoam.org \\ / A nd | Version: 6 \\/ M anipulation | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class volScalarField; location "0"; object alphat; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 2 -1 0 0 0 0]; internalField uniform 0; boundaryField { inlet { type calculated; value uniform 0; } outlet { type calculated; value uniform 0; } atmosphere { type calculated; value uniform 0; } hotWall { type alphatJayatillekeWallFunction; Prt 0.85; value $internalField; } #includeEtc "caseDicts/setConstraintTypes" } // ************************************************************************* // |
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July 2, 2020, 13:31 |
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#5 |
Senior Member
Agustín Villa
Join Date: Apr 2013
Location: Alcorcón
Posts: 313
Rep Power: 15 |
Hi,
there is a recirculation as fluid cannot go out. Please take a look into this
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July 3, 2020, 09:59 |
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#6 |
Member
Alex
Join Date: May 2019
Posts: 36
Rep Power: 6 |
Hi,
I took a look to all the points listed but I still have some questions, because the model is not working well yet:
You told me that you worked on this problem already, can you find your case folder? It would be a big help for me. Thanks for the help |
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July 3, 2020, 15:27 |
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#7 |
Senior Member
Agustín Villa
Join Date: Apr 2013
Location: Alcorcón
Posts: 313
Rep Power: 15 |
Hi Sedullo,
here you have an article where I discuss about this topic. My computational domain differs from yours at the leading edge of the plate. I add a volume below the plate to ensure there is flow coming from the bottom. By doing this I sensure the growing of the boundary layer. In my case I did LES, so I went into unsteady simulations. This is why I asked you about
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July 8, 2020, 07:46 |
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#8 |
Member
Alex
Join Date: May 2019
Posts: 36
Rep Power: 6 |
Hi,
Sorry for the late answer, I read your paper and it is really interesting for the purpose of my reasearch. My objective is to simulate the natural convection boundary layer with laminar flow of a flat vertical wall and then plot how the Nusselt number is varying along the wall, afterwards I should build another vertical wall but this time not flat but wavy, and do the same. At the end I will compare the two plots to see which has "better" Nusselt Number. Honestly I am quite new in CFD and I do not know if a steady or a transient simulation is good for my purpose. I will work later on the analysis of the Nusselt Number, my first goal is to simulate the boundary layer flow. Whatever suggestion you have for the setting up of the domain and of the boundary conditions is very very welcome. My main questions that I could not understand from your paper are:
Thank you so much for the help |
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July 22, 2020, 15:57 |
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#9 |
Member
Alex
Join Date: May 2019
Posts: 36
Rep Power: 6 |
Hi agustinvo, honestly my knowledge of OpenFOAM is limited, I am not able to calculcate Nusselt Number as you suggested.
At the moment I used the wallheatflux utility because I thought that in some way I could get Nusselt from there, but I do not know yet how to use this results. I have a couple of question:
Please let me know what you think |
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