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-   -   which Solver for Hot Cold Water mix (http://www.cfd-online.com/Forums/openfoam/106932-solver-hot-cold-water-mix.html)

uwsa September 12, 2012 12:55

which Solver for Hot Cold Water mix
 
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.

sachin September 18, 2012 03:40

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 ...

inf.vish July 30, 2013 07:39

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.

nimasam July 30, 2013 15:58

use bouyantBoussinqSimpleFoam

inf.vish July 30, 2013 22:36

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

inf.vish July 31, 2013 03:19

1 Attachment(s)
i have attached an image showing what exactly i want to do.

nimasam July 31, 2013 04:32

what contour is it? is it temperature contour?

inf.vish July 31, 2013 04:35

Yes that is the temperature contour.

inf.vish July 31, 2013 04:36

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.

nimasam July 31, 2013 04:43

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 :)

inf.vish July 31, 2013 04:45

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.

nimasam July 31, 2013 04:55

1 Attachment(s)
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 :)

inf.vish July 31, 2013 04:58

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.

nimasam July 31, 2013 08:35

i suggest you to read the first chapter of userguide and work with some tutorial cases ;) you will find how to assign your BCs

and about
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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