CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM Running, Solving & CFD

BC settings to expand pressure on atmosphere - simpleFoam / totalPressure

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   February 8, 2010, 06:22
Default BC settings to expand pressure on atmosphere - simpleFoam / totalPressure
  #1
Member
 
Join Date: Nov 2009
Location: Munich
Posts: 43
Rep Power: 7
sErik is on a distinguished road
Hi Foamers,

I have a problem with the definition of boundary conditions.
I'm running a relativly easy case - standard backward facing step - with simpleFoam (kepsilon turbulence model) to compare the OF results with some other calculations.

At the inlet I have a velocity of 6,02 m/s and at the outlet I want the pressure to expand to normal atmospheric pressure (101325 Pa). My problem is, that I don't realy know, how to set the correct conditions for the inlet/outlet.

At the moment I have for U
Quote:
inlet
{
type fixedValue;
value uniform (6.02 0 0);
}

outlet
{
type fixedValue;
value uniform (0 0 0);
}

wall
{
type fixedValue;
value uniform (0 0 0);
}
and for p
Quote:
inlet
{
type zeroGradient;
}

outlet
{type fixedValue;
value uniform 0;
}

wall
{
type zeroGradient;
}
My boundarys are
Quote:
inlet
{
type patch;
physicalType inlet;
}
outlet
{
type patch;
physicalType outlet;
}
With these settings, the simulation runs fine, but it's not exactly what I need.

I tried totalPressure with these settings - wall stays the same:
for p
Quote:
inlet
{
type totalPressure;
p0 uniform 1.01325e+05;
U U;
phi phi;
rho none;
psi none;
gamma 1.4;
}
outlet
{
type totalPressure;
p0 uniform 1.01325e+05;
U U;
phi phi;
rho none;
psi none;
gamma 1.4;
}
for U
Quote:
inlet
{
type fixedValue;
value uniform (6.02 0 0);
}

outlet
{
type zeroGradient;
}
But then the simulation crashes after a few steps:
Quote:
Time = 0.4

DILUPBiCG: Solving for Ux, Initial residual = 0.4226, Final residual = 0.0131669, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.385886, Final residual = 0.00659647, No Iterations 1
GAMG: Solving for p, Initial residual = 0.993287, Final residual = 0.00404666, No Iterations 1
time step continuity errors : sum local = 14029.9, global = -1.97454, cumulative = -52.1146
DILUPBiCG: Solving for epsilon, Initial residual = 0.245904, Final residual = 0.00112502, No Iterations 1
bounding epsilon, min: -5.08864e+15 max: 2.93019e+16 average: 6.86567e+11
DILUPBiCG: Solving for k, Initial residual = 0.796412, Final residual = 0.0271624, No Iterations 1
bounding k, min: -7.85411e+07 max: 3.01688e+10 average: 2.10361e+06
ExecutionTime = 5.7 s ClockTime = 6 s

Time = 0.5

DILUPBiCG: Solving for Ux, Initial residual = 0.00899943, Final residual = 3.74612e-05, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.0728675, Final residual = 9.68172e-05, No Iterations 1
GAMG: Solving for p, Initial residual = 0.976204, Final residual = 0.00756845, No Iterations 5
time step continuity errors : sum local = 211598, global = 3456.42, cumulative = 3404.3
DILUPBiCG: Solving for epsilon, Initial residual = 2.35526e-05, Final residual = 3.37908e-07, No Iterations 1
bounding epsilon, min: -1.98511e+19 max: 4.34557e+20 average: 1.11602e+16
DILUPBiCG: Solving for k, Initial residual = 0.000959334, Final residual = 1.61051e-05, No Iterations 1
bounding k, min: -2.44986e+14 max: 9.10124e+14 average: 8.71869e+09
ExecutionTime = 6.37 s ClockTime = 7 s

Time = 0.6

DILUPBiCG: Solving for Ux, Initial residual = 0.587131, Final residual = 0.00365698, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.381925, Final residual = 0.0271016, No Iterations 1
GAMG: Solving for p, Initial residual = 1, Final residual = 0.0082871, No Iterations 7
time step continuity errors : sum local = 4.51584e+49, global = -1.07389e+49, cumulative = -1.07389e+49
DILUPBiCG: Solving for epsilon, Initial residual = 1, Final residual = 0.00710696, No Iterations 1
bounding epsilon, min: -7.62782e+71 max: 8.5466e+73 average: 1.90599e+69
DILUPBiCG: Solving for k, Initial residual = 1, Final residual = 0.00716964, No Iterations 1
bounding k, min: -6.71536e+58 max: 3.06377e+59 average: 1.93931e+55
ExecutionTime = 7.11 s ClockTime = 8 s

Time = 0.7

DILUPBiCG: Solving for Ux, Initial residual = 1, Final residual = 0.00874036, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 1, Final residual = 0.00873079, No Iterations 1
#0 Foam::error:rintStack(Foam::Ostream&) in "/opt/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libOpenFOAM.so"
#1 Foam::sigFpe::sigFpeHandler(int) in "/opt/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libOpenFOAM.so"
#2 ?? in "/lib/libc.so.6"
#3 Foam::PCG::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/opt/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libOpenFOAM.so"
#4 Foam::GAMGSolver::solveCoarsestLevel(Foam::Field<d ouble>&, Foam::Field<double> const&) const in "/opt/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libOpenFOAM.so"
#5 Foam::GAMGSolver::Vcycle(Foam::PtrList<Foam::lduMa trix::smoother> const&, Foam::Field<double>&, Foam::Field<double> const&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::PtrList<Foam::Field<double> >&, Foam::PtrList<Foam::Field<double> >&, unsigned char) const in "/opt/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libOpenFOAM.so"
#6 Foam::GAMGSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/opt/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libOpenFOAM.so"
#7 Foam::fvMatrix<double>::solve(Foam::dictionary const&) in "/opt/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libfiniteVolume.so"
#8 main in "/opt/OpenFOAM/OpenFOAM-1.6/applications/bin/linux64GccDPOpt/simpleFoam"
#9 __libc_start_main in "/lib/libc.so.6"
#10 _start at /usr/src/packages/BUILD/glibc-2.9/csu/../sysdeps/x86_64/elf/start.S:116
It's clear, that bounding k and epsilon diverge, but I don't understand why. With the first settings, I get fine results.


How do I have to specify the correct BC for the velocity/pressure for my case?
I would realy appreciate your help!

Regards,
Erik


€dit
This is my k-file
Quote:
inlet
{
type fixedValue;
value uniform 0.0748;
}
outlet
{
type zeroGradient;
}
wall
{
type kqRWallFunction;
value uniform 0.0748;
}
This is epsilon
Quote:
inlet
{
type fixedValue;
value uniform 0.960;
}
outlet
{
type zeroGradient;
}
wall
{
type epsilonWallFunction;
value uniform 0.960;
}
sErik is offline   Reply With Quote

Old   June 15, 2011, 02:49
Question simpleFoam totalpressure vof
  #2
Member
 
hamdi
Join Date: Mar 2009
Posts: 72
Rep Power: 8
hamcer is on a distinguished road
Hello Foamers,

I'm doing a test case on an injector using simplefoam, and I am a bit stuck on the implementation of boundary condition on the pressure (how to use the totalpressure).
when I look at the velocity profile they are not the same as in vof. The jet is horizontal in vof, and isn't in simplefoam

Can someone help me, it's crucial for my thesis.

Thank in advance.


Last edited by hamcer; June 20, 2011 at 13:06.
hamcer is offline   Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Laminar simpleFoam and inviscid simpleFoam herenger OpenFOAM Running, Solving & CFD 7 July 11, 2013 06:27
SimpleFoam TotalPressure loss prapanj OpenFOAM Running, Solving & CFD 1 July 30, 2009 11:09


All times are GMT -4. The time now is 17:35.