We are in the process of validating OpenFOAM against other CFD codes, wind tunnel tests and field measurements using benchmarking test cases defined by a Japanese academic society (or its journal article if you prefer paper form) for urban wind environment predictions. If you follow the link you'll find 8 cases, cases A - H, simulating urban environments with varying reality, ranging from simple blocks to realistic urban terrains. Among those we have finished cases A - F, and in the process of publishing the case data so that any OpenFOAM users can reproduce our results. The test cases Elvis mentioned
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Takuya |
Hi Guillaume,
I'm sorry for late reply. I'd like to answer your 1st and 4th questions (thanks a lot Takuya for answering 2nd and 3rd) Quote:
blockMesh (in single): 1 min. decomposePar (in single): 1 min. snappyHexMesh (in 16 cpu parallel): 40 mins. reconstructParMesh (in single): 17 mins. Quote:
far, but have a look at e.g.: http://dl.dropbox.com/u/3609076/Vent...per_ver.2_.pdf http://dl.dropbox.com/u/3609076/Vent...2009100201.pdf Quote:
Moreover I couldn't validate LES or DES simulation since I didn't have any measurement data to compare with in this case. As Elvis and Takuya mentioned in previous posts, I uploaded OpenFOAM tutorial cases which predict urban wind environment and validate with wind tunnel measurement data. Though these cases use RAS model as turbulent model, but it's easy to change it to VLES or DES if you share the mesh for the RAS calculation. So please try validating these benchmark tests with VLES or DES model and report the results if you have spare time :) Masashi |
hello..
I am hijacking this post. I am simulating a flow over an urban area, but i am working in 2D, i am obtaining convegence with simpleFOam but when view in paraview its as if no wind has enter my domain.. Can you please advice me on the boundary conditions used? I tried SLip and inletoutlet all in vain... I am using RAS model, with GAMG solver . My east side of domain is inlet and the three remaining sides ie north south and west are outflow where my wind is supposed to go ... But i need help in the boundarycondition.. kind regards izna |
Izna,
Probably best to create a new post for your question... Can you post your U and p directory? Julien |
hi.. thanks a lot for the reply.. below is my u and p dire.. also sides means the north and south sides... its in 2D
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Thanks. Nothing obviously wrong with the two files. Can you send some more information (mesh, solver output, screenshot)?
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hi.. meshwas done in Gambit.. converted to FOam..
solver PCG i am putingh FV solution here Quote:
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we can see it has not simulated to convergence.. but how to make it converge without crashing???
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when i do the BC as symmetryPlane i obtain the errors...
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Izna,
What is your question/request for assistance? Your post 9.10: Quote:
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i am sorry.. its just i am trying a lot of different solvers..
My question is i want to obtain a velocity start from the east side of my domain.. but i am obtaining the followig picture..:( |
No drama. It is getting clearer. I can't see anything wrong from the dictionary, but have to admit that I have not done 2D simulations... So there are a few of the "tricks" that I do not know.
Could you post a link to a complete case for download and try? |
yesh am going to send a link..thnaks heaps Julien..
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Hi Izna,
Thanks for sending the case through. It helps - even though I have not tried to run the model. Below are two suggestions: 1) North and South boundaries: In your setup, these are defined as "outlet" boundary conditions. I understand that you are using this approach as you would like to allow for exit/re-entry of fluid. This set of condition is what creates in your case the high in-velocity observed in the picture. My recommendation is to change these conditions to symmetry (for the north and south faces only). If you are concerned about flow exit/re-entry, you can evaluate the impact of the domain size (in width) on the variable of interest by doubling the domain size in the width direction. 2) West boundary condition: The setup is a zero velocity gradient and zero pressure. I personally prefer to change it to an inlet/outlet setup where the backflow velocity is specified as zero. It operates as the outlet you defined as long as the flow is going out, but prevent backflow. I found this approach more stable. Although this may have some impact, the above suggestion should be sufficient. Let me know if you try any of the above and if they work (as a separate thread). |
hello Julien
http://www.cfd-online.com/Forums/ope...tml#post456673 this is the new thread please do check. :( izna |
Hey Guys, your discussions are really helpful, thanks!
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