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Heat Transfer from a Rough Cylinder in Tunnel RE=2.2E5 M=0.07 

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December 6, 2010, 08:56 
Heat Transfer from a Rough Cylinder in Tunnel RE=2.2E5 M=0.07

#1 
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Guilherme da Silva
Join Date: Aug 2010
Location: Sao Paulo  Brazil
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Dear All,
I am running in rhoSimpleFoam (OpenFoam 1.7.x), realizableKE, rough wall functions, a cylinder (D=0.15 m and length=0.5 m) with roughness (equivalent sandgrain height, Ks=0.00135 m) in a tunnel of cross section (0.9 by 0.5 meters) operating with flow of Re=2.2E5 and inlet Tu=0.45%. some assumptions for simulation:  upstream tunnel length = 10*D downstreal tunnel length = 20*D atmospheric back pressure imposition = 101325 Pa inlet X velocity = 23.45 m/s intlet Tu = 1% inlet mut/mu = 50 first prysm layer at 1e3 m last prysm layer at 6.645e2 m number of layers 26 prysm growth rate 1.05 Nominal Ks = 0.00135 m despite the laminarturbulent transition is located at 1.2 degree (found by integral method and Rek=600 criteria for nominal Ks), OpenFoam does not have a laminartransition yet available. inlet air temperature = 303.15 K surface temperature DeltaT = 6 K mutRoughWallFunction used for momentum mutalphatWallFunction used for heat It has been hard to get convergence with kEpsilon, realizableKE and even kOmegaSST. I have tried several configurations and followed recommendations of several forums threads. Sometimes the residuals stall or oscillates, which is common in CFD. As I am interested in forces (by analogy with heat transfer), this may not as critical as it looks. However, I do not see an expected symmetry in the U or P solution (contours) as I got in other softwares like CFD++ or even SolidWorks Flow Simulation. Other issue is that p residuals stall at very high value, well above 1e2. fvSchemes: Code:
ddtSchemes { default steadyState; } gradSchemes { default Gauss linear; grad(U) cellMDLimited Gauss linear 1; grad(p) cellMDLimited Gauss linear 1; } divSchemes { default none; div(phi,U) Gauss linearUpwindV cellMDLimited Gauss linear 1; div((muEff*dev2(grad(U).T()))) Gauss linear; div(phi,h) Gauss linearUpwind cellMDLimited Gauss linear 1; div(phi,epsilon) Gauss upwind; //div(phi,omega) Gauss upwind; div(phi,k) Gauss upwind; div(phid,p) Gauss upwind; div(U,p) Gauss upwind; } laplacianSchemes { default none; laplacian(muEff,U) Gauss linear limited 0.5; laplacian(alphaEff,h) Gauss linear limited 0.5; laplacian((rhoA(U)),p) Gauss linear limited 0.5; laplacian((rho*rAU),p) Gauss linear limited 0.5; laplacian(DepsilonEff,epsilon) Gauss linear limited 0.5; //laplacian(DomegaEff,omega) Gauss linear limited 0.5; laplacian(DkEff,k) Gauss linear limited 0.5; laplacian(1,p) Gauss linear limited 0.5; laplacian((rho*(1A(U))),p) Gauss linear limited 0.5; } interpolationSchemes { default linear; interpolate(U) linear; } snGradSchemes { default limited 0.5; } fluxRequired { default no; p ; } Code:
solvers { p { solver GAMG; tolerance 1e10; relTol 0.001; smoother GaussSeidel; cacheAgglomeration true; nCellsInCoarsestLevel 10; agglomerator faceAreaPair; mergeLevels 1; nSweeps 2; nPreSweeps 0; nPostSweeps 2; } h { solver PBiCG; preconditioner DILU; tolerance 1e08; relTol 0.005; } k { solver smoothSolver; smoother GaussSeidel; nSweeps 2; tolerance 1e08; relTol 0.005; } epsilon { solver smoothSolver; smoother GaussSeidel; nSweeps 2; tolerance 1e08; relTol 0.005;; } U { solver smoothSolver; smoother GaussSeidel; nSweeps 2; tolerance 1e08; relTol 0.005; } } SIMPLE { nCorrectors 3; nNonOrthogonalCorrectors 5; pRefCell 0; pRefValue 0; pMin pMin [ 1 1 2 0 0 0 0 ] 10000; rhoMax rhoMax [ 1 3 0 0 0 0 0 ] 4; rhoMin rhoMin [ 1 3 0 0 0 0 0 ] 0.5; } relaxationFactors { p 0.2; rho 0.1; U 0.5; k 0.5; epsilon 0.5; h 0.2; } Code:
application rhoSimpleFoam; startFrom startTime; startTime 0; stopAt endTime; endTime 2500; deltaT 1; writeControl timeStep; writeInterval 100; purgeWrite 0; writeFormat binary; writePrecision 6; writeCompression uncompressed; timeFormat general; timePrecision 6; graphFormat raw; runTimeModifiable yes; Code:
Mesh stats points: 242333 faces: 1613006 internal faces: 1584830 cells: 720237 boundary patches: 7 point zones: 0 face zones: 0 cell zones: 0 Overall number of cells of each type: hexahedra: 0 prisms: 316888 wedges: 0 pyramids: 0 tet wedges: 0 tetrahedra: 403349 polyhedra: 0 Checking topology... Boundary definition OK. Point usage OK. Upper triangular ordering OK. Face vertices OK. Number of regions: 1 (OK). Checking patch topology for multiply connected surfaces ... Patch Faces Points Surface topology cylinder 12188 6158 ok (nonclosed singly connected) topbottom 6802 4340 ok (nonclosed singly connected) topbottom2 6820 4349 ok (nonclosed singly connected) side1 964 552 ok (nonclosed singly connected) inlet 220 131 ok (nonclosed singly connected) outlet 220 131 ok (nonclosed singly connected) side2 962 551 ok (nonclosed singly connected) Checking geometry... Overall domain bounding box (1.47689 0.45 0.25) (2.97689 0.45 0.25) Mesh (nonempty, nonwedge) directions (1 1 1) Mesh (nonempty) directions (1 1 1) Boundary openness (1.20477e17 4.90409e16 7.44393e18) OK. Max cell openness = 3.20177e16 OK. Max aspect ratio = 7.90905 OK. Minumum face area = 3.77495e06. Maximum face area = 0.0165682. Face area magnitudes OK. Min volume = 3.95177e09. Max volume = 0.000473042. Total volume = 1.99538. Cell volumes OK. Mesh nonorthogonality Max: 70.0352 average: 22.7072 *Number of severely nonorthogonal faces: 1. Nonorthogonality check OK. <<Writing 1 nonorthogonal faces to set nonOrthoFaces Face pyramids OK. Max skewness = 1.0217 OK. Mesh OK. End PS: the main reference is the paper below... [1] Achenbach, E., The effect of surface roughness on the heat transfer from a circular cylinder to the cross flow of air, Int. J. Heat and Mass Transfer, Vol. 20, 1977, pp. 35969. paper link Last edited by aerothermal; December 6, 2010 at 08:57. Reason: typo 

December 6, 2010, 16:21 
boundary conditions

#2 
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Guilherme da Silva
Join Date: Aug 2010
Location: Sao Paulo  Brazil
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Dear All,
See attached the boundary conditions folder "0". Regards, Guilherme 

December 8, 2010, 08:49 
Cylinder Cp data

#3 
Senior Member
Guilherme da Silva
Join Date: Aug 2010
Location: Sao Paulo  Brazil
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Dear All,
I have not posted yet the mesh but I will do in next few days. See attached the experimental data for Cp over a rough and smooth cylinder regarding the case above. There is a correlation for Cp over the rough cylinder fitted in range 2.2E05 < Re_D < 4.0E06 by Stefanini et. al[1] that may help the analysis of the problem: a < 2.646 b < 1.194 cpCorr < 1a*sin(b*thetaRad)^2 where 0<thetaRad<pi/2. Regards, Guilherme [1] Stefanini, L. M., Silvares, O. M., Silva, G. A. L., and Zerbini, E. J. G. J., Boundary , Heat Transfer on Iced Cylinders, AIAA Paper 20107672, AIAA Atmospheric and Space Environments Conference, Toronto, Ontario, Aug. 25, 2010, American Institute of Aeronautics and Astronautics, Reston, 2010. Regards, Guilherme Last edited by aerothermal; December 8, 2010 at 09:24. Reason: add more info 

December 18, 2010, 11:12 
Convergence?

#4 
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Guilherme da Silva
Join Date: Aug 2010
Location: Sao Paulo  Brazil
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Dear All,
Maybe this subject is not so interesting to everybody but I will continue posting on that because I think that some day some people may need information about the issue. So I am describing what I did to get some (very) preliminary convergence despite not so satisfactory for my purposes (heat transfer). See attached the residuals, continuity, forces and heat transfer along the iterations (time in steadyState). Only the main residuals are outside the zip, for the rest see zip file. Also I am posting the the "/0" and "/system" folders (see zip). As the "constant" folder is too big (approx 10 MB) to be placed here, I uploaded it to a virtual folder at address below: https://www.4shared.com/file/Vb8fJFoY/constant.html It appears that OF goes well until iteration 200, when it starts diverging and oscillating about at higher level of residuals than the level reached in 200 time. This is caused mainly by the wake effect. Despite I could filter most of it, there is some residual oscillation that could not be killed. Is it my wrong impression that OF171 is not truly steady state solver so the wake cannot be averaged or filtered out? See attached also, the results of the velMag countours and Cp for OF171 compared with those of CFD++ (http://www.metacomptech.com). The OF171 results are in blue. Both software use the realizableKE model, assume wall functions to simulate momentum and heat transfer over the rough surface and have the same mesh. However, CFD++ has the laminarturbulent transition and OF171 does not have since it is full turbulent only. The transition in CFD++ was triggered at 1.5 degree (of the cylinder) that is actually happened in experimental runs. The mesh was developed in mesh generator MIME (http://www.metacomptech.com), exported as CGNS by MIME, and converted from CGNS to FOAM by OF1.5dev tool cgnsToFoam. Due to some errors in conversion from CGNS format to FOAM, I had to autoPatch to find the patch faces of the mesh since the converter only recognized the internal mesh. As I have the heat transfer and Cf results validated I will post them all. Regards, Guilherme da Silva Last edited by aerothermal; December 18, 2010 at 11:46. Reason: grammar 

May 12, 2011, 12:41 
Results!

#5 
Senior Member
Guilherme da Silva
Join Date: Aug 2010
Location: Sao Paulo  Brazil
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Dear All,
I managed to get convergence in OF1.6ext but not in OF1.7.1 with same configuration files in folders 0/ constant/ system/. I will post them shortly. In order to make it work, I had to modify the alphatWallFunction to a new alphatRoughWallFunction proposed by our team. I changed also the mutRoughWallFunction to be compliant with models used in icing literature. I hope to post them in a repository soon and make it available to everybody. Meanwhile, I am posting the results. For those who want details, we are publishing the paper in next SAE Aircraft and Engine Icing International Conference in Chicago. http://papers.sae.org/2011380023/ Last edited by pete; July 18, 2011 at 06:42. Reason: Removed affiliation 

July 17, 2011, 09:34 

#6 
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Guilherme da Silva
Join Date: Aug 2010
Location: Sao Paulo  Brazil
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I will organize data and post here soon.
Last edited by aerothermal; July 26, 2011 at 15:35. 

December 20, 2011, 09:47 
validation of new alphatWallFunction for heat transfer over rough walls

#7 
Senior Member
Guilherme da Silva
Join Date: Aug 2010
Location: Sao Paulo  Brazil
Posts: 105
Rep Power: 7 
Dear colleagues,
The recent results of validation performed in OpenFoam 1.6ext and 1.7.1 can be found at our last paper: http://www.ats4i.com.br/en/publicati...11380023.pdf Comments and questions are welcome in order to improve the model and the code. Regards, Aerothermal 

May 21, 2013, 07:11 

#8  
Senior Member
HECKMANN Frédéric
Join Date: Jul 2010
Posts: 236
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Quote:
Your sentence perfectly matchs my case and I'm really interestet in your work. I have read your paper and I have to say that you made a great job. I went to take a look on your website and on the links you give at the end of your paper. As appendix, you say that your code is available on code.google.com but it seems that the files have been deleted. May I ask you to share it with me ? Did you try to implement it into OF 2.x ? Regards, Fred 

May 22, 2013, 11:02 

#9 
Senior Member
Guilherme da Silva
Join Date: Aug 2010
Location: Sao Paulo  Brazil
Posts: 105
Rep Power: 7 
Dear Frederick,
Yes. All files are there but not in binary download section. The source is in the repository. To close that you will need Mercurial package. Please google it to check how it works. To know more about Mercurial: http://mercurial.selenic.com/downloads/ After installing mercurial, type the command: hg clone https://gasilva%40ats4i.com.br@code....ts4iopentools/ Regards, Guilherme  aerothermal 

May 23, 2013, 04:12 

#10 
Senior Member
HECKMANN Frédéric
Join Date: Jul 2010
Posts: 236
Rep Power: 8 
Thank you very much for your answer.
For those who also want to get the source code with Ubuntu: 1) Install Mercurial Code:
sudo aptget install mercurial Code:
hg clone https://gasilva%40ats4i.com.br@code.google.com/p/ats4iopentools/ 

Tags 
cylinder, heat transfer, icing, roughness, wall function 
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