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

Boundary Conditions for reactingFoam

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

Reply
 
LinkBack Thread Tools Display Modes
Old   February 1, 2015, 20:25
Default Boundary Conditions for reactingFoam
  #1
New Member
 
Join Date: Jul 2013
Posts: 9
Rep Power: 4
okstatecheme is on a distinguished road
I'm running a reactingFoam case with no reactions to track chemical species transport coming out the top of a vent stack with a crosswind.



Using the following thermophysical properties.


type hePsiThermo;
mixture reactingMixture;
transport sutherland;
thermo janaf;
energy sensibleEnthalpy;
equationOfState perfectGas;
specie specie;



I get about 1 second of run time (out of 20 seconds desired) before the simulation crashes. I get a temperature spike, the time step decreases to infinitesimally small increments, then the simulation crashes. Not sure what phenomena is going on here.



Here's the last log entry:
Code:
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
smoothSolver:  Solving for Ux, Initial residual = 1.63336e-16, Final residual = 1.63336e-16, No Iterations 0
smoothSolver:  Solving for Uy, Initial residual = 2.63377e-17, Final residual = 2.63377e-17, No Iterations 0
smoothSolver:  Solving for Uz, Initial residual = 2.56103e-17, Final residual = 2.56103e-17, No Iterations 0
smoothSolver:  Solving for O2, Initial residual = 6.29731e-14, Final residual = 6.29731e-14, No Iterations 0
smoothSolver:  Solving for H2O, Initial residual = 6.8088e-14, Final residual = 6.8088e-14, No Iterations 0
smoothSolver:  Solving for CO2, Initial residual = 2.01932e-20, Final residual = 2.01932e-20, No Iterations 0
smoothSolver:  Solving for H2S, Initial residual = 2.14111e-20, Final residual = 2.14111e-20, No Iterations 0
smoothSolver:  Solving for h, Initial residual = 3.94866e-16, Final residual = 3.94866e-16, No Iterations 0
min/max(T) = 237.675, 1102.75
DICPCG:  Solving for p, Initial residual = 2.40778e-15, Final residual = 2.40778e-15, No Iterations 0
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 1.04371e-07, global = -4.49885e-09, cumulative = -4.31315e-05
DICPCG:  Solving for p, Initial residual = 2.40778e-15, Final residual = 2.40778e-15, No Iterations 0
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 1.04371e-07, global = -4.49885e-09, cumulative = -4.3136e-05
DICPCG:  Solving for p, Initial residual = 2.40778e-15, Final residual = 2.40778e-15, No Iterations 0
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 1.04371e-07, global = -4.49885e-09, cumulative = -4.31405e-05
smoothSolver:  Solving for omega, Initial residual = 2.97292e-19, Final residual = 2.97292e-19, No Iterations 0
smoothSolver:  Solving for k, Initial residual = 1.84934e-18, Final residual = 1.84934e-18, No Iterations 0
ExecutionTime = 7202.62 s  ClockTime = 7393 s

Courant Number mean: 1.20973e-10 max: 1.04921
deltaT = 6.04121e-29
--> FOAM Warning : 
    From function Time::operator++()
    in file db/Time/Time.C at line 1055
    Increased the timePrecision from 647 to 648 to distinguish between timeNames at time 1.1452
Time = 1.145202402849336831280879778205417096614837646484375
I'm guessing the fault has to do with my pressure/velocity boundary conditions?



p { margin-bottom: 0.1in; line-height: 120%; }
The ground (Bottom patch) is a wall, as is Stack, with a circular inletOutlet velocity patch (Sides). The Top is slip boundary condition. There is another inlet (Inlet) at the top of the stack where the chemicals are injected into the flow domain.


Here are the U & p bc's:



U

Code:
dimensions      [0 1 -1 0 0 0 0];

internalField   uniform (20 0 0);

boundaryField
{
    inlet
    {
        type            fixedValue;
        value           uniform (0 0 8.4);
    }
    bottom
    {
        type            fixedValue;
    value        uniform (0 0 0);
    }
    sides
    {
        type            inletOutlet;
    inletValue    uniform (20 0 0);
    value        uniform (20 0 0);
    }
    stack
    {
    type        fixedValue;
    value        uniform (0 0 0);
    }
    top
    {
        type            slip;
    }
}
p


Code:
dimensions      [1 -1 -2 0 0 0 0];

internalField   uniform 1e5;

boundaryField
{
    inlet
    {
        type            zeroGradient;
    }
    bottom
    {
        type            zeroGradient;
    }
    sides
    {
        type            totalPressure;
        U               U;
        phi             phi;
        rho             none;
        psi             none;
        gamma           1.4;
        p0              uniform 1e5;
    }
    stack
    {
    type        zeroGradient;
    }
    top
    {
        type            slip;
    }
}
Lastly the fvSolution dict:
Code:
solvers
{
    p
    {
        solver           PCG;
        preconditioner   DIC;
        tolerance        1e-7;
        relTol           0.01;
    }

    pFinal
    {
        $p;
        tolerance        1e-7;
        relTol           0.0;
    }

    "(rho|U|h|k|omega)"
    {
        solver          smoothSolver;
        smoother        symGaussSeidel;
        tolerance       1e-06;
        relTol          0.1;
    }

    "(rho|U|h|k|omega)Final"
    {
        $U;
    tolerance    1e-7;
        relTol          0;
    }

    Yi
    {
        $hFinal;
    }
}

PIMPLE
{
    momentumPredictor yes;
    nOuterCorrectors  1;
    nCorrectors     3;
    nNonOrthogonalCorrectors 0;
}

relaxationFactors
{
    fields
    {
        "p.*"           0.3;
        "rho.*"         1;
    }
    equations
    {
        "(U|h|k||omega).*" 0.7;
    }
}
Anybody see any issues with the BC?? Any insight as to what is causing the crash.
Attached Images
File Type: jpg walls.jpg (11.9 KB, 4 views)
File Type: jpg walls&sides.jpg (15.4 KB, 3 views)
File Type: jpg pressure.jpg (17.4 KB, 4 views)
File Type: jpg velocity.jpg (18.0 KB, 4 views)
File Type: png residuals.png (32.9 KB, 4 views)
okstatecheme 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
sliding mesh problem in CFX Saima CFX 45 September 22, 2015 10:53
GETVAR Error in Multiband Monte Carlo Radiation Simulation with Directional Source silvan CFX 3 June 16, 2014 09:49
Question about heat transfer coefficient setting for CFX Anna Tian CFX 1 June 16, 2013 06:28
boundary conditions and mesh exporting vaina74 Open Source Meshers: Gmsh, Netgen, CGNS, ... 2 May 27, 2010 09:38
Trimmed cell and embedded refinement mesh conversion issues michele OpenFOAM Other Meshers: ICEM, Star, Ansys, Pointwise, GridPro, Ansa, ... 2 July 15, 2005 04:15


All times are GMT -4. The time now is 22:09.