|
[Sponsors] |
August 5, 2013, 13:32 |
Pressure BC´s simpleFoam
|
#1 |
Senior Member
James
Join Date: May 2013
Posts: 116
Rep Power: 12 |
Hi everyone,
Anyone knows how to modelate a pressure driven flow in a channel with simpleFoam solver? When I try to specify fixedValue at inlet and outlet( for p) and zeroGradient in the same boundaries (for U) then the results explodes with no physical meaning. I have tried some combinations (pressureInletVelocity, inletOutlet...). I need to know if it´s possible to do and if not, which solver can I use? Please HELP (I am getting crazy with that issue) Thank you so much |
|
August 5, 2013, 22:28 |
|
#2 |
Member
Vishal
Join Date: Jul 2013
Posts: 73
Rep Power: 12 |
I am also stuck on the same problem. The boundary conditions i put seem correct. fixed value condition for p is correct. for U you need to put pressureInletVelocity at the inlet and zeroGradient at the outlet. But using these BCs my solution won't converge and the results look weird. I will post if i solve the problem correctly.
|
|
August 6, 2013, 11:07 |
|
#3 |
Senior Member
James
Join Date: May 2013
Posts: 116
Rep Power: 12 |
Thanks for the reply,
I am trying new bc´s that involves totalPressure, but nothing seems to run. I got converged results, but without physical meaning. I will let you know if I find a solution, but I think simpleFoam does not allow this kind of setup (maybe we have to do some C++ programming for obtain a suitable boundary condition in terms of pressure...) It´s weird, because FLUENT do the calculation without problems.... |
|
August 6, 2013, 11:09 |
simpleFoam BBCC
|
#4 |
New Member
Juan Pablo Toro Labbe
Join Date: Jun 2013
Location: Davis CA
Posts: 7
Rep Power: 12 |
Hi there, did you review the "turbulent flow over a backward-facing step" (PitzDaily case)?
Because you are interested in the pressure gradient and not in the pressure itself, you can fix the pressure, e.g p=0 Pa at outlet, the program will calculate the pressure field, and thus, you will have the pressure gradient. Regards, JP |
|
August 6, 2013, 11:31 |
|
#5 |
Senior Member
James
Join Date: May 2013
Posts: 116
Rep Power: 12 |
Hi Juan Pablo,
Thanks for the suggestion, I will review this tutorial. I need to fix pressure gradient between inlet and outlet, because velocity is not known (and I am interested for example in computing flow rate), so is the pressure difference what induces fluid motion. I´ll try what you suggest, keeping my fingers crossed. Thank you so much |
|
August 6, 2013, 11:33 |
|
#6 |
Senior Member
James
Join Date: May 2013
Posts: 116
Rep Power: 12 |
Now I am reading slowly what JP has said. I think his suggestion is suitable if you want to calculate pressure gradient, but this is not my case. The pressure at inlet and outlet is known and fixed!
Thanks anyway! |
|
August 6, 2013, 22:47 |
|
#7 |
Member
Vishal
Join Date: Jul 2013
Posts: 73
Rep Power: 12 |
Hi James,
Yesterday i solved the problem of Poiseuille flow (laminar) using simpleFoam. The problem is that the solution won't converge even after running for 100000 iterations. The solution conforms with Poiseuille's law even though convergence is not reached. If you want i can post my files. I have done it for an axisymmetric wedge. |
|
August 7, 2013, 05:01 |
|
#8 |
Senior Member
James
Join Date: May 2013
Posts: 116
Rep Power: 12 |
Hi Vishal,
Yes please, let me see the files so I can compare. I am triying to use fixedGradient, pressureInletVelocity, totalPressure...but nothing give me good results, the simulation gives very high values (for a pressure gradient of 20 Pa I expect velocitites of about 4/5 m/s) for velocity and pressure. I am a beginner to OF so I am not sure if programming is needed for that kind of setup. Thanks for your help (if you need I can post my files too) |
|
August 7, 2013, 23:16 |
|
#9 |
Member
Vishal
Join Date: Jul 2013
Posts: 73
Rep Power: 12 |
Hi James,
I am also a beginner. Here is my case. The fluid i have considered is water at 20 degree celcius. The only problem I am having is of convergence. If you can shed some light on it then that would be great. laminarPipe_poiseuille.zip |
|
August 8, 2013, 05:25 |
|
#10 |
Senior Member
James
Join Date: May 2013
Posts: 116
Rep Power: 12 |
Thanks Vishal,
As I expected, we have the same kind of BC´s. The only difference is that I use some nonOrthogonalCorrectors because I have a tetraedral+prism mesh. I´ll continue researching and if I know what´s happening I´ll let you know. I have been reading in the forum and it looks like all the people have some problems with pressure driven flows (many complaints about the big magnitudes of variables when Dirichlet pressure BC´s are applied). We are in contact, if I find something new I´ll post it here Cheers, James |
|
August 11, 2013, 23:36 |
|
#11 |
Member
Vishal
Join Date: Jul 2013
Posts: 73
Rep Power: 12 |
Hi James,
I was able to get convergence on a 3D cylindrical pipe with the same boundary conditions. It takes a lot many iterations (431) as compared to simple velocity driven flow (97). |
|
August 12, 2013, 06:54 |
|
#12 |
Senior Member
James
Join Date: May 2013
Posts: 116
Rep Power: 12 |
Hi Vishal,
Then it looks like the problems are the complex geometry and maybe the mesh, because I am trying to do this in a complex channel and simulation explodes! I have tried an advise given in the forum: I initialize the internalField for pressure with the same value than I put in the outlet. At first it works fine, but when resiudals are about 1e-02, they start to rise up, and values for pressure and velocity are near of 1e+12. I´ll make some experiments with cylindrical geometries, because if they work fine then I´ll be sure that the problem is geometry and mesh, not OF model. Thanks, we are in contact for anything! |
|
August 12, 2013, 23:02 |
|
#13 |
Member
Vishal
Join Date: Jul 2013
Posts: 73
Rep Power: 12 |
Oh. You can try refining your boundary meshes.
Yeah try the same problem on a simple cylinder. You want to simulate Poiseuille flow but what is the geometry you are using? |
|
January 2, 2014, 03:18 |
Floating Point core dumped
|
#14 |
Senior Member
Join Date: Sep 2013
Location: Bangalore India
Posts: 134
Rep Power: 12 |
Hi,
I rad the discussion made by you all. And implemented similar boundary conditions to my simulations ( Flow through a ball valve) . But I am getting the following error. #0 Foam::error:rintStack(Foam::Ostream&) in "/home/sml5kor/OpenFOAM/OpenFOAM-2.2.1/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #1 Foam::sigFpe::sigHandler(int) in "/home/sml5kor/OpenFOAM/OpenFOAM-2.2.1/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #2 in "/lib/x86_64-linux-gnu/libc.so.6" #3 Foam::multiply(Foam::Field<double>&, Foam::UList<double> const&, Foam::UList<double> const&) in "/home/sml5kor/OpenFOAM/OpenFOAM-2.2.1/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #4 void Foam::multiply<Foam::fvPatchField, Foam::volMesh>(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) in "/home/sml5kor/OpenFOAM/OpenFOAM-2.2.1/platforms/linux64GccDPOpt/lib/libincompressibleTurbulenceModel.so" #5 Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > Foam:perator*<Foam::fvPatchField, Foam::volMesh>(Foam::tmp<Foam::GeometricField<doub le, Foam::fvPatchField, Foam::volMesh> > const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) in "/home/sml5kor/OpenFOAM/OpenFOAM-2.2.1/platforms/linux64GccDPOpt/lib/libincompressibleRASModels.so" #6 Foam::incompressible::RASModels::kEpsilon::correct () in "/home/sml5kor/OpenFOAM/OpenFOAM-2.2.1/platforms/linux64GccDPOpt/lib/libincompressibleRASModels.so" #7 in "/home/sml5kor/OpenFOAM/OpenFOAM-2.2.1/platforms/linux64GccDPOpt/bin/simpleFoam" #8 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6" #9 in "/home/sml5kor/OpenFOAM/OpenFOAM-2.2.1/platforms/linux64GccDPOpt/bin/simpleFoam" Floating point exception (core dumped) Can anybody help me ? My case turbulent parameters are as below k=0.00036 m2/s2 epsilon = 0.00014 m3/s2 nuT = 1.04 X 10^-7 m2/s Density = 800 kg/m3 and Inlet presure = 5 bar outlet pressure = 1 bar (atmospheric pressure) |
|
February 27, 2014, 09:10 |
Boundary conditions for simpleFOAM
|
#15 |
Member
Join Date: Feb 2014
Posts: 57
Rep Power: 12 |
Hi,
I want to apply a total pressure at inlet (4 bar) and a pressure outlet (0 bar) boundary conditions. May you give me some advides? In fact, I tried the files p and U given in the folder Poiseill's flow but I was unable to run the simulation! Thanks. |
|
August 29, 2014, 16:33 |
|
#16 |
Member
Christian
Join Date: Apr 2014
Posts: 74
Rep Power: 12 |
Hi all,
after several tests I was able to get meaningful results for pressure-driven fluxes in a duct using: p Inlet: fixed Value uniform 10000 (inlet pressure - remember to divide it by density!) outlet: fixed value uniform 0 U inlet: fixed Value uniform (10 0 0) outlet: fixed value uniform (10 0 0) with the same fixed value you will force mass conservation and results are ok. this make sense if inlet and outlet have the same area. if different area (such as pitzdaily,) try U outlet: type inletOutlet; inletValue uniform (10 0 0); //or different velocity, try to estimate it from inelt/outlet ratio and mass conservation formulas; value uniform (10 0 0); Let me know if it works and if this approach is correct, that's the only way I could get meaningful physical results! |
|
April 23, 2015, 12:19 |
Pressure BC´s simpleFoam
|
#17 |
Member
alvaro
Join Date: Apr 2015
Posts: 33
Rep Power: 11 |
Hi people,
I know has been a long time since last post. I have the same problem with simpleFoam and the pressure driven flow. I'd like to know if you solved the problem (if still remember). I have tried everything, even what Vishal suggested. And whatever I do it diverges always just after the first iteration. Code:
Starting time loop Time = 1 smoothSolver: Solving for Ux, Initial residual = 1, Final residual = 0.000640509, No Iterations 2 smoothSolver: Solving for Uy, Initial residual = 1, Final residual = 0.000755479, No Iterations 2 #0 Foam::error::printStack(Foam::Ostream&) in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #2 in "/lib/x86_64-linux-gnu/libc.so.6" #3 Foam::GAMGSolver::scale(Foam::Field<double>&, Foam::Field<double>&, Foam::lduMatrix const&, Foam::FieldField<Foam::Field, double> const&, Foam::UPtrList<Foam::lduInterfaceField const> const&, Foam::Field<double> const&, unsigned char) const in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #4 Foam::GAMGSolver::Vcycle(Foam::PtrList<Foam::lduMatrix::smoother> const&, Foam::Field<double>&, Foam::Field<double> const&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::PtrList<Foam::Field<double> >&, Foam::PtrList<Foam::Field<double> >&, unsigned char) const in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #5 Foam::GAMGSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #6 Foam::fvMatrix<double>::solveSegregated(Foam::dictionary const&) in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libfiniteVolume.so" #7 Foam::fvMatrix<double>::solve(Foam::dictionary const&) in "/opt/openfoam230/platforms/linux64GccDPOpt/bin/simpleFoam" #8 in "/opt/openfoam230/platforms/linux64GccDPOpt/bin/simpleFoam" #9 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6" #10 in "/opt/openfoam230/platforms/linux64GccDPOpt/bin/simpleFoam" Floating point exception (core dumped) p Code:
dimensions [0 2 -2 0 0 0 0]; internalField uniform 0; boundaryField { front { type empty; } back { type empty; } inlet { type fixedValue; value uniform 1000; } outlet { type fixedValue; value uniform 0; } sym { type symmetryPlane; } wall1 { type zeroGradient; } wall2 { type zeroGradient; } } Code:
dimensions [0 1 -1 0 0 0 0]; internalField uniform (0 0 0); boundaryField { front { type empty; } back { type empty; } inlet { type fixedValue; value uniform (8.3 -5 0); // type pressureInletVelocity; // value uniform (0 0 0); } outlet { type fixedValue; value uniform (10 0 0); // type zeroGradient; // type inletOutlet; // inletValue uniform (0 0 0); // value uniform (0 0 0); } sym { type symmetryPlane; } wall1 { type fixedValue; value uniform (0 0 0); } wall2 { type fixedValue; value uniform (0 0 0); } } |
|
February 5, 2016, 05:27 |
|
#18 |
New Member
Lisa
Join Date: Dec 2015
Posts: 8
Rep Power: 10 |
Hey Alvaro,
Did you solve that Problem? I have the same Problem and can't find an answer.. Thanks!! |
|
March 1, 2017, 09:17 |
With Hydrogen simpeFoam
|
#19 |
New Member
cfdRocker
Join Date: Jun 2011
Posts: 5
Rep Power: 14 |
Hi all,
I have a question almost similar to this case with simpleFoam. I searched other forum but found this was the closest to my problem. I have a case , consider a simple MICRO channel with hydrogen as fluid. Density of hydrogen is very less - 0.0824 kg/m3. My inlet pressure is 2bar and outlet pressure is 1.5bar. If I want to divide pressure by density as said by OpenFoam then I think its nearly INLET- 2427184.46 and accordingly the outlet. This value is very high and when I run simpleFoam , continuity error increases nearly to the order e+12 and results are not physical. My values 0/p internalField uniform 0; I did change this to 100000 but dint work out. WALL zeroGradient INLET type fixedValue 2427184.4; Accordingly OUTLET BC. 0/U INLET type pressureInletVelocity; value uniform(0 0 0); OUTLET type inletOutlet; inletValue uniform(0.0001 0 0); value uniform(0.0001 0 0); WALL type noslip; I am expecting the velocity to be very low because we know it should be laminar. Please let me know if I am going wrong somewhere. Also let me know if you need more information. Regards, Manoj |
|
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Calculation of the Governing Equations | Mihail | CFX | 7 | September 7, 2014 06:27 |
High pressure residual simpleFoam | CiccioPasticcio | OpenFOAM Running, Solving & CFD | 6 | March 5, 2013 21:20 |
Pressure BC for combustion chamber | Giuki | FLUENT | 1 | July 19, 2011 11:35 |
pressure in simpleFoam | mediode | OpenFOAM Running, Solving & CFD | 2 | March 6, 2011 14:33 |
mapping of pressure field (simplefoam to cavitatingFoam) | siddharameshwara | OpenFOAM Running, Solving & CFD | 14 | February 15, 2011 08:59 |