which Solver for Hot Cold Water mix

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 September 12, 2012, 12:55 which Solver for Hot Cold Water mix #1 New Member   Erkan Join Date: May 2010 Posts: 9 Rep Power: 9 Hi all Foam Users, I would like to simulate a pipe flow with two inflows ( first inflow cold 35 Celsius) (second inflow 100 Celsius) and one outflow with the mixture of both. The pressure is about 8 MPa. I checked the tutorials but could not find a corresponding case. Does anybody know which solver could be useful for my case? Thanks a lot.

 September 18, 2012, 03:40 #2 Member   Sachin Kanetkar Join Date: Mar 2009 Posts: 57 Rep Power: 10 Hi ... you already have icoFoam case for flow mixing from two inlets ... same as fluent tutorial case ... you just need to add the temperature equation to icoFoam (wiki page already there explaining it) and run the case ...

 July 30, 2013, 07:39 #3 Member   Vishal Join Date: Jul 2013 Posts: 73 Rep Power: 6 Can you share your insights on the above problem? I would like to solve a similar problem. T joint mixing of two streams of water at different temperatures.

 July 30, 2013, 15:58 #4 Senior Member   Nima Samkhaniani Join Date: Sep 2009 Location: Tehran, Iran Posts: 1,245 Blog Entries: 1 Rep Power: 18 use bouyantBoussinqSimpleFoam __________________ Telegram channel (https://telegram.me/openfoam4Iranian) My Weblog in Persian(http://openfoam.blogfa.com/) My Personal Website (http://nimasamkhaniani.ir/)

 July 30, 2013, 22:36 #5 Member   Vishal Join Date: Jul 2013 Posts: 73 Rep Power: 6 The problem with buoyantBoussinesqSimpleFoam is that i can set temperature boundary conditions at the two inlets but the fluid as such does not flow at the said temperature. The fluid simply carries the heat with it. I ran the case with buoyantBoussinesqSimpleFoam and looked at the temperature profiles at different times and i can see how to fluid carries the heat. That is not my aim.I want fluid at 600K to enter the inlet. Kindly tell me the boundary conditions for having a fluid at 600K enter the inlet if you are using buoyantBoussinesqSimpleFoam. I found a thesis paper which says about mixing of hot and cold water with turbulence and he has used dnsFoam to solve. Also, he hasn't mentioned the codes. Can you guide me further on this simple problem. I have been stuck on this problem for three days

July 31, 2013, 03:19
#6
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Vishal
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i have attached an image showing what exactly i want to do.
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 July 31, 2013, 04:32 #7 Senior Member   Nima Samkhaniani Join Date: Sep 2009 Location: Tehran, Iran Posts: 1,245 Blog Entries: 1 Rep Power: 18 what contour is it? is it temperature contour? __________________ Telegram channel (https://telegram.me/openfoam4Iranian) My Weblog in Persian(http://openfoam.blogfa.com/) My Personal Website (http://nimasamkhaniani.ir/)

 July 31, 2013, 04:35 #8 Member   Vishal Join Date: Jul 2013 Posts: 73 Rep Power: 6 Yes that is the temperature contour.

 July 31, 2013, 04:36 #9 Member   Vishal Join Date: Jul 2013 Posts: 73 Rep Power: 6 This example is very simple to solve on fluent. Why the difficulty in solving in OpenFOAM? I understand that buoyantBoussinesqSimpleFoam can be used. But how do i achieve the fluid entering at different temperatures.

 July 31, 2013, 04:43 #10 Senior Member   Nima Samkhaniani Join Date: Sep 2009 Location: Tehran, Iran Posts: 1,245 Blog Entries: 1 Rep Power: 18 it's also easy in OpenFOAM, you need to define two inlets as you defines your geometry! give one inlet T1 and the other one T2 There is no hard task here __________________ Telegram channel (https://telegram.me/openfoam4Iranian) My Weblog in Persian(http://openfoam.blogfa.com/) My Personal Website (http://nimasamkhaniani.ir/)

 July 31, 2013, 04:45 #11 Member   Vishal Join Date: Jul 2013 Posts: 73 Rep Power: 6 I did that. But that boundary condition just implies that the two inlets are at T1 and T2. It does not imply that the fluid entering them is at T1 and T2.

July 31, 2013, 04:55
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Nima Samkhaniani
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its an well-known elbow mixing problem, you can see at picture (temperature contour) that two hot and cold waters are mixing together here!
i used buoyantBoussinesqSimpleFoam! for this problem. so i did not get what the problem is. when you assign a fixed temperature at inlet you force the solver to consider the inlet fluid with that temperature , i dont understand why do u separate them
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 July 31, 2013, 04:58 #13 Member   Vishal Join Date: Jul 2013 Posts: 73 Rep Power: 6 Okay. Thanks. I didn't know how OpenFOAM was treating that particular temperature boundary condition. I was thinking it as a Heater kept at the inlet, sort of a film of heat. Thanks once again can you share your boundary conditions for p,U,p_rgh and T. I am a bit confused on p_rgh and p.

July 31, 2013, 08:35
#14
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Nima Samkhaniani
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i suggest you to read the first chapter of userguide and work with some tutorial cases you will find how to assign your BCs

Quote:
 p_rgh and p
you need just assign BC for p_rgh which is pressure minus hydrostatic effect, p will be BC write then by solver, for p, BC can be consider as calculated
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 May 28, 2017, 06:04 #15 New Member   arianna sterpi Join Date: May 2017 Posts: 6 Rep Power: 2 How should be the velocity profile at the outlet section for this problem?

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