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October 24, 2007, 02:40 |
I am new to OpenFoam. Can some
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#1 |
New Member
Erik Bjørn
Join Date: Mar 2009
Location: Denmark
Posts: 5
Rep Power: 17 |
I am new to OpenFoam. Can someone tell where to find more information about the different boundary conditions, apart from table 6.4. in the user guide? I have already searched this forum, and I am aware that the information is available in the code. However, I cannot understand the code. Is there a plain-text description somewhere?
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October 24, 2007, 07:27 |
I'm afraid: No
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#2 |
Assistant Moderator
Bernhard Gschaider
Join Date: Mar 2009
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I'm afraid: No
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Note: I don't use "Friend"-feature on this forum out of principle. Ah. And by the way: I'm not on Facebook either. So don't be offended if I don't accept your invitation/friend request |
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November 19, 2007, 06:24 |
Hi Erik
Look here for the b.c
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#3 |
New Member
Maximilian Graser
Join Date: Mar 2009
Location: Stuttgart, Germany
Posts: 18
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Hi Erik
Look here for the b.c.: .../OpenFOAM/src/finiteVolume/fields/fvPatchFields/derived There you will find the different boundary conditions - some even with a short description and example - if you open the *.C and *.H files with an editor |
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November 20, 2007, 02:26 |
Thank you for the tip. However
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#4 |
New Member
Erik Bjørn
Join Date: Mar 2009
Location: Denmark
Posts: 5
Rep Power: 17 |
Thank you for the tip. However, I cannot see much in the way of descriptions. At least not in a form understandable to me. But then again, I'm just a simple engineer, not an expert in CFD and C++ programming.
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November 20, 2007, 03:56 |
And I'm just a Student in the
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#5 |
New Member
Maximilian Graser
Join Date: Mar 2009
Location: Stuttgart, Germany
Posts: 18
Rep Power: 17 |
And I'm just a Student in the 2nd year and neighter a C++ expert
The description I'm talking of is not in the code; its in the "foreword" just below the GNU License written as a comment Look at fvPatchFields/derived/massFlowRateInletVelocity.H (open with an editor) for example; there you can see a good description how to use this boundary in the comments |
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November 20, 2007, 05:03 |
OK, I see what you mean now. T
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#6 |
New Member
Erik Bjørn
Join Date: Mar 2009
Location: Denmark
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OK, I see what you mean now. Thanks. I am afraid the description is missing in many of the BC's. But at least now I know where to look for them in future versions.
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November 20, 2007, 05:48 |
Is the shown description what
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#7 |
New Member
Maximilian Graser
Join Date: Mar 2009
Location: Stuttgart, Germany
Posts: 18
Rep Power: 17 |
Is the shown description what you're looking for?
Maybe I can help with a few of the others where the description is missing. Also there are some descriptions of boundarys throughout this forum; you just have to search a little. |
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November 20, 2007, 06:41 |
Yes, the shown description is
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#8 |
New Member
Erik Bjørn
Join Date: Mar 2009
Location: Denmark
Posts: 5
Rep Power: 17 |
Yes, the shown description is a great help. Right now, I am interested in finding out the differences between different boundaries to do with pressure:
totalPressure pressureInletVelocity pressureInletUniformVelocity pressureInletOutletVelocity pressureDirectedInletVelocity pressureDirectedInletOutletVelocity fixedFluxPressure fixedFluxBuoyantPressure freestreamPressure |
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November 20, 2007, 07:05 |
Have you looked at the User Ma
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#9 |
New Member
Maximilian Graser
Join Date: Mar 2009
Location: Stuttgart, Germany
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Have you looked at the User Manual?
pressureInletVelocity totalPressure pressureInletOutletVelocity pressureDirectedInletVelocity pressureDirectedInletOutletVelocity are explained in Cahpter 6.2/Table 6.4/ page U-141 fixedFluxPressure I'd guess is a BC where you set the Flux as a fixedValue an the Pressure is calculated according to the Flux fixedFluxBuoyantPressure should be almost the same with additional heattransfer (->buoyant) but i realy dont know it exactly additional info: http://www.cfd-online.com/OpenFOAM_D...tml?1175063998 there are a lot more BC topics in the forum...search it |
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November 20, 2007, 07:06 |
Maybe I should describe the pr
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#10 |
New Member
Erik Bjørn
Join Date: Mar 2009
Location: Denmark
Posts: 5
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Maybe I should describe the problems I am presently working with. Maybe somebody can tell me what to do:
Problem 1: Cross-contamination (or short-circuit) from a ventilation exhaust to an intake (on the outside of a building), under influence of wind. The exhaust and intake can both be either constant velocity or mass flow boundaries. Wind must be velocity boundary. I need a "far field" boundary, which I think should be "constant pressure". How do I implement this in OF? Problem 2: A fan blows air through a heat exchanger via an irregular duct geometry. The heat exchanger consists of very many fine plates, which I don't want to simulate. I know how the heat exchanger behaves with regard to pressure drop. I imagine I can simulate it as a pressure boundary, I am just unsure which is appropriate. |
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November 20, 2007, 07:10 |
I'd say "far field" is the sam
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#11 |
New Member
Maximilian Graser
Join Date: Mar 2009
Location: Stuttgart, Germany
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I'd say "far field" is the same as "freestream"
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March 24, 2008, 17:33 |
Hi
I am new OpenFoam user is
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#12 |
New Member
Onur Dundar
Join Date: Mar 2009
Location: Davis, CA, US
Posts: 7
Rep Power: 17 |
Hi
I am new OpenFoam user is there any Boundary condition which represents uniform flow in Open channel. I tried fixed velocity but caused problem just connected to the atmosphere patch. In fact I saw many different type of boundary condition in field library. For example I tried massFlowRateInletVelocity in 0/U file type massFlowRateInletVelocity value 12.849 but this gave error How can I understand the correct information from .C file of .H file of that boundary condition. |
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April 14, 2008, 03:50 |
Hi
try
inlet
{
type mas
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#13 |
Senior Member
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Hi
try inlet { type massFlowRateInletVelocity massFlowRate 0.2// 0.2kg s^-1 } |
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April 17, 2008, 10:32 |
Hi,
Section 6.2.3 of the us
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#14 |
Member
Jason Dale
Join Date: Mar 2009
Location: UK
Posts: 80
Rep Power: 17 |
Hi,
Section 6.2.3 of the user guide tells me that there is a boundary type called 'calculated' where the boundary field is derived from other fields. I have tried searching the forum but cannot really find anything about how to use this. I'm curious about two things. 1/ I want to set the flowrate at an inlet to a certain value that is found from a polynomial that relates the flowrate and pressure, eg a polynomial fitted to a centrifugal pump Flowrate-Pressure curve. So, based on the pressure at the last timestep, I adjust the flowrate at the boundary in order to mimic the response of a centrifugal pump. 2/ Is it possible to have a pair of boundaries in unconnected meshes where the fluid flowing into one boundary is set from the fluid flowing out of the other boundary. So, that if I managed to do No 1 I could adjust the flowrates in the unconnected meshes automatically. Is this possible or do I have to do some programming. Thanks Jason |
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August 11, 2009, 03:56 |
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#15 |
Senior Member
Prapanch Nair
Join Date: Mar 2009
Location: Bangalore, India
Posts: 105
Rep Power: 17 |
Hey,
there is something called the directMapped boundary, where you can set your inlet as the flow at another patch witch is x distance in front or behind it. |
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August 11, 2009, 09:38 |
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#16 |
Senior Member
Prapanch Nair
Join Date: Mar 2009
Location: Bangalore, India
Posts: 105
Rep Power: 17 |
Hey,
there is something called the directMapped boundary, where you can set your inlet as the flow at another patch witch is x distance in front or behind it. |
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October 24, 2009, 12:21 |
Robin B.C
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#17 |
New Member
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Hi
Does anyone know how shall I model the following Robin B.C? dC/dY=alpha*C where C is the scalar concentration, alpha is constant and Y is the wall-normal direction. It means the gradient is proportional to the concentration which is not known a priori. Thanks in advance Kaveh |
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December 16, 2009, 04:01 |
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#18 |
Senior Member
Claus Meister
Join Date: Aug 2009
Location: Wiesbaden, Germany
Posts: 241
Rep Power: 17 |
Hey folks!
I created a geometry and a mesh in salome. My mesh contains patches in the interior of the geometry. Does anybody know how to set a "continuity patch" in OpenFOAM? |
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