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October 24, 2010, 08:54 |
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#21 |
Senior Member
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October 24, 2010, 09:01 |
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#22 |
Senior Member
Join Date: Mar 2009
Posts: 225
Rep Power: 18 |
Is it required to use one of the turbulence models as long as one only cares about general temperature distribution? Let's say I don't care much about eddies development, all I care about is just temperature distribution through the building structure. Is turbulence a key factor?
Just to speed up the process, I would try to simplify my simulation as much as possible, therefore skip turbulence. Is it an acceptable, common procedure? Thanks, K |
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October 24, 2010, 09:56 |
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#23 |
New Member
Join Date: May 2009
Posts: 14
Rep Power: 16 |
I will post my settings tomorrow, I don't have access to it now I was using the k omega SST for this one I think.
@ paka: if you chose to stay within the laminar setup, you don't need any turbulence model. Just chose the "laminar" model and switch turbulence to "off". It depends on your task if that makes sense. I wouldn't suggest it for a setup like the one above. There are some papers out there, discussing the adequate turbulence modeling for a given task.. |
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October 24, 2010, 18:14 |
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#24 |
Senior Member
Join Date: Mar 2009
Posts: 225
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Yes, thank you, but my question was rather towards what is a general procedure, tendency in solving such problems, where one only cares how temperature spreads across the building?
I just don't really imagine why turbulence would play important role in HVAC. Can anyone enlighten me Thanks! K |
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October 25, 2010, 04:46 |
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#25 |
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Join Date: May 2009
Posts: 14
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In HVAC, we have low Reynolds numbers and high turbulence ratios (10-75%). Especially the turbulent normal stresses near walls and the transition effects at the inlets influence the flow.
Airflows underneath the ceiling feature certain phenomena like the “coanda effect” and the rearrangement of turbulent normal stresses which is in the end effecting the temperature distribution as well as the velocity. A laminar flow cannot consider these aspects, standard turbulence models also do not catch up completely.. “The user of a turbulence model is more like a test pilot.. [..]” //Michael |
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February 16, 2012, 04:56 |
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#26 | |
New Member
Join Date: Feb 2012
Location: Slovenia, Europe
Posts: 2
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Quote:
Good day! I would like to make a case, where a room with 2 windows (inlet and outlet for ventilation) is defined. I would like to define this geometry in a stl file with some program (http://www.rhino3d.com/) but I don't know how to implement that window is a different patch than walls (different BC). Could this be done like in tutorials/mesh/snappyHexMesh/snappyMultiRegionHeater where there are more than 1 stl file each as a different patch? I don't want to try to solve my problem like in tutorials/mesh/snappyHexMesh/motorBike where inlet and outlet are defined in blockMeshDict and are not on stl defined geometry (motorbike). I completed a few tutorials and modified one of them succesfully (stl file generated in Mathematica, meshed with sHM, result is below). I was browsing this forum and found above quoted post and would politely ask, if it is possible, anyone could send me case files for this or similar ventilation problem. My e-mail: podergajs.matej@gmail.com Thank you for any reply and sorry for posting so long arter the last post. Matej Podergajs |
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January 29, 2015, 02:01 |
chtregionsimpleFoam
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#27 |
Member
sa har
Join Date: Aug 2014
Posts: 34
Rep Power: 11 |
hello,I started to leran openfoam.i have proplem when i work with chtregion simplefoam and i cant solve this error.
this error is: Create time --> FOAM FATAL IO ERROR: keyword regions is undefined in dictionary "/home/sahar/Desktop/fasle4/constant/regionProperties" file: /home/sahar/Desktop/fasle4/constant/regionProperties from line 18 to line 20. From function dictionary::lookupEntry(const word&, bool, bool) const in file db/dictionary/dictionary.C at line 402. FOAM exiting sahar@sahar-S451LB:~/Desktop/fasle4$ can you hlep me?how can solve this problem. |
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January 29, 2015, 21:41 |
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#28 | |||
Senior Member
Alex
Join Date: Oct 2013
Posts: 337
Rep Power: 21 |
Hello, and welcome to the forum!
Quote:
Flash forward Mode ON Quote:
Flash forward Mode OFF Quote:
TIP (as a newbie gift): This error says that you haven't defined the regions field within the constant/regionProperties dictionary or maybe you don't even have such dictionary within the constant directory. If you still don't know what I am talking about, please, work hard with the basic case you can find in the page I gave you. Flash forward Mode ON You are welcome, again! Flash forward Mode OFF Hope it is useful for you to start playing with OF and chtMultiRegion cases! Regards, Alex Btw, this is a very old post, you could have posted it somewhere else or opened a new thread in order to get help.
__________________
Web site where I present my Master's Thesis: foamingtime.wordpress.com The case I talk about in this site was solved with chtMultiRegionSimpleFoam solver and involves radiation. Some basic tutorials are also resolved step by step in the web. If you are interested in these matters, you are invited to come in! |
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January 30, 2015, 01:26 |
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#29 | |
Member
sa har
Join Date: Aug 2014
Posts: 34
Rep Power: 11 |
Quote:
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February 12, 2015, 18:46 |
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#30 | |
New Member
Juan David Rodriguez P
Join Date: Jan 2015
Location: Milano
Posts: 20
Rep Power: 11 |
Quote:
Continuity error cannot be removed by adjusting the outflow. How did you set your inlet and outlet BC? Thank you in advance. |
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