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May 22, 2014, 04:42
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Floating point exception (core dumped) in transonicMRFDyMFoam
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#21 |
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Senior Member
Join Date: Sep 2013
Location: Bangalore India
Posts: 134
Rep Power: 12  |
Hi ,
Here with I have attached BC and Constant files which gives the lower pressure ratio and revolution per second (RPS) as per your suggestion but i am finding Floating point exception (core dumped). The out put log file also attached. Please let me know if i have any discrepancies. Please guide me . I am seriously in trouble as my thesis need to be submitted in July. Need to validate my case with OpenFOAM results with experimental values. how to give Mass flow rate input at Velocity file at INLET patch ? Last edited by sam.ho; May 22, 2014 at 04:47. Reason: missed a question |
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May 23, 2014, 04:19
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No convergence
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#22 |
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Senior Member
Join Date: Sep 2013
Location: Bangalore India
Posts: 134
Rep Power: 12 |
Hi,
I have changed some BC in velocity. As i knew flow rate for my case I gave as follows Code:
INLET
{
type flowRateInletVelocity;
flowRate 0.0049454545;
value uniform (0 0 0);
}
OUTLET //11
{
type zeroGradient;
}
Code:
INLET
{
type zeroGradient;
}
OUTLET
{
type fixedValue;
value uniform 105000.0;
}
Code:
internalField uniform 303;
boundaryField
{
INLET //1
{
type isentropicTotalTemperature;
p p; // name of static pressure field
T0 uniform 973.0; // absolute total temperature field
p0 uniform 125000; // absolute total presure field
value uniform 960.0; // initial value atmospheric temperature is considered
}
OUTLET //11
{
type zeroGradient;
}
Mass convergence is not happening and temperature variation at inlet and outlet are high. Out let temperature expected to vary within 200 but in my case out velocity is remaining almost same "internalField uniform 303". I gave inlet total temperature as 973 K. But why is it varying with iterations. Its an input given to case and should be constant Rite ? please let me know how to get convergence. Regards, sam Last edited by sam.ho; May 23, 2014 at 04:25. Reason: missed a question |
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May 27, 2014, 03:43
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#23 | |
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New Member
Join Date: May 2011
Posts: 28
Rep Power: 14 |
Quote:
1) at inlet, specify total pressure, total temperature and direction of velocity direction 2)at outlet, specify static pressure, its value can be slightly lower than the total pressure at inlet; 3) set the rotation speed to zero, 4) in the file named "U", set the initial velocity vector in the domain and on the boundary to (0 0 0) the above settings make the turbine like a nozzle. you can check it. In my cases, I usually do it like this.Good luck. |
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May 27, 2014, 04:52
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#24 |
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Senior Member
Join Date: Sep 2013
Location: Bangalore India
Posts: 134
Rep Power: 12 |
Could you please explain me about rotational sign used in MRDzone file ?
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May 28, 2014, 06:56
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No convergence with transonicMRFDyMFOAM
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#25 |
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Senior Member
Join Date: Sep 2013
Location: Bangalore India
Posts: 134
Rep Power: 12 |
Hi,
I have simulated the case. Up to 1400 iterations everything went well. Ang got the results almost converged. Which is as follows Code:
Time = 1400 MassFlows: INLET = 0.050998309 MassFlows: OUTLET = 0.051097883 Averages of p : INLET = 122879.91 OUTLET = 105000 Averages of rho : INLET = 0.44092278 OUTLET = 0.42706291 Averages of T : INLET = 968.66311 OUTLET = 861.43023 Averages of U : INLET = (-93.909463 0 0) OUTLET = (-1.7016498 2.2553501 142.98454) The error message was Code:
From function specieThermo<thermo>::T(scalar f, scalar T0, scalar (specieThermo<thermo>::*F)(const scalar) const, scalar (specieThermo<thermo>::*dFdT)(const scalar) const) const
in file /home/sml5kor/OpenFOAM/OpenFOAM-1.6-ext/src/thermophysicalModels/specie/lnInclude/specieThermoI.H at line 73
Maximum number of iterations exceeded. Rescue by HJ
Can u share your case set up (only BC's MRFzone and system) ? Regards, Sangamesh Hosur |
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June 24, 2014, 03:12
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transonicMRFDyMFoam
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#26 |
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Senior Member
Join Date: Sep 2013
Location: Bangalore India
Posts: 134
Rep Power: 12 |
HI Dowlee,
I have set up the case of radial inflow turbine passage and case is running absolutely fine. But after convergence whyc there is a difference in mass flows at the inlet and outlet. which is shown below Code:
MassFlows: INLET = 0.062517835 MassFlows: OUTLET = 0.054917385 Averages of p : INLET = 121854.22 OUTLET = 105000 Averages of rho : INLET = 0.43810996 OUTLET = 0.39981185 Averages of T : INLET = 966.74467 OUTLET = 912.84935 Averages of U : INLET = (-116.88216 0 0) OUTLET = (-2.1964329 -14.212135 160.62) And also outlet temperature at the turbine outlet is too high as my TempFile is as below Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM Extend Project: Open Source CFD |
| \\ / O peration | Version: 1.6-ext |
| \\ / A nd | Web: www.extend-project.de |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
location "0";
object T;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 0 0 1 0 0 0];
internalField uniform 900.0;
boundaryField
{
INLET //1
{
type isentropicTotalTemperature;
p p; // name of static pressure field
T0 uniform 973.0; // absolute total temperature field
p0 uniform 125000; // absolute total presure field
value uniform 900.0; // initial value atmospheric temperature is considered
}
SHR_UPS //2
{
type zeroGradient;
}
HUB_UPS //3
{
type zeroGradient;
}
IFC1_UPS_TO_IMP //4
{
type overlapGgi;
}
RAD_HUB //5
{
type zeroGradient;
}
RAD_SHR //6
{
type zeroGradient;
}
RAD_BLADE_0 //7
{
type zeroGradient;
}
BLADE_TIP //8
{
type zeroGradient;
}
IFC2_UPS_TO_IMP //9
{
type overlapGgi;
}
IFC1_IMP_TO_UPS //10
{
type overlapGgi;
}
OUTLET //11
{
type zeroGradient;
}
HUB_DWS //12
{
type zeroGradient;
}
SHROUD_DWS //13
{
type zeroGradient;
}
IFC2_IMP_TO_DWS //14
{
type overlapGgi;
}
PERIODIC1 //15
{
type cyclicGgi;
}
PERIODIC2 //16
{
type cyclicGgi;
}
PER1_DWS //17
{
type cyclicGgi;
}
PER2_DWS //18
{
type cyclicGgi;
}
PER1_UPS //19
{
type cyclicGgi;
}
PER2_UPS //20
{
type cyclicGgi;
}
}
// ************************************************************************* //
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June 24, 2014, 04:09
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#27 | |
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New Member
Join Date: May 2011
Posts: 28
Rep Power: 14 |
Quote:
Hi I think mostly this is related to the mesh. implement the following command and have a look at the mesh quality, checkMesh -allTopology -allGeometry -constant now the newest version for openfoam extend project is foam-extend-3.1. And inside it there is a sovler named steadyCompressibleMRFFoam which can be used for turbomachinery. You can have a try by using this newly release solver. |
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June 24, 2014, 04:22
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#28 |
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Senior Member
Join Date: Sep 2013
Location: Bangalore India
Posts: 134
Rep Power: 12 |
Output of the command
Code:
sml5kor@BMH301562:~/OpenFOAM/sml5kor-1.6-ext/run/TURBINE_cyclicGGI_2/finel_merge_2/Case_with_initial_volcity_field_high_k-omega$ checkMesh -allTopology -allGeometry -constant
/*---------------------------------------------------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM Extend Project: Open source CFD |
| \\ / O peration | Version: 1.6-ext |
| \\ / A nd | Web: www.extend-project.de |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
Build : 1.6-ext
Exec : checkMesh -allTopology -allGeometry -constant
Date : Jun 24 2014
Time : 13:50:10
Host : BMH301562
PID : 32477
Case : /home/sml5kor/OpenFOAM/sml5kor-1.6-ext/run/TURBINE_cyclicGGI_2/finel_merge_2/Case_with_initial_volcity_field_high_k-omega
nProcs : 1
SigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time
Create polyMesh for time = constant
Initializing the GGI interpolator between master/shadow patches: PER1_UPS/PER2_UPS
Initializing the GGI interpolator between master/shadow patches: PERIODIC1/PERIODIC2
Initializing the GGI interpolator between master/shadow patches: PER1_DWS/PER2_DWS
Time = constant
Mesh stats
all points: 652866
live points: 652866
all faces: 1885491
live faces: 1885491
internal faces: 1813845
cells: 616556
boundary patches: 20
point zones: 0
face zones: 13
cell zones: 6
Overall number of cells of each type:
hexahedra: 616556
prisms: 0
wedges: 0
pyramids: 0
tet wedges: 0
tetrahedra: 0
polyhedra: 0
Checking topology...
Boundary definition OK.
Point usage OK.
Upper triangular ordering OK.
Topological cell zip-up check OK.
Face vertices OK.
Face-face connectivity OK.
*Number of regions: 3
The mesh has multiple regions which are not connected by any face.
<<Writing region information to "constant/cellToRegion"
Checking patch topology for multiply connected surfaces ...
Patch Faces Points Surface topology Bounding box
INLET 4402 4536 ok (non-closed singly connected) (0.028963776 -0.0085061541 4.3901804e-19) (0.030186862 0.0085049543 0.00652312)
SHR_UPS 1491 1584 ok (non-closed singly connected) (0.023331164 -0.0085043668 0.0065231199) (0.030186087 0.0085049543 0.00652312)
HUB_UPS 1491 1584 ok (non-closed singly connected) (0.023330961 -0.0085058132 4.3901804e-19) (0.030186099 0.0085035082 4.3901805e-19)
PER1_UPS 1302 1386 ok (non-closed singly connected) (0.023330961 -0.0085061541 4.3901804e-19) (0.0289643 -0.0068504314 0.00652312)
PER2_UPS 1302 1386 ok (non-closed singly connected) (0.023331164 0.0068497398 4.3901804e-19) (0.028964653 0.0085049543 0.00652312)
IFC1_UPS_TO_IMP 4402 4536 ok (non-closed singly connected) (0.023330961 -0.0068515966 4.3901804e-19) (0.024316069 0.0068509049 0.00652312)
PERIODIC1 4216 4347 ok (non-closed singly connected) (0.0051635397 -0.0095592735 4.3901804e-19) (0.023331303 -0.0027305049 0.01864559)
PERIODIC2 4216 4347 ok (non-closed singly connected) (0.0061525676 -0.00010298083 4.3901804e-19) (0.0233315 0.0068509049 0.01864559)
RAD_HUB 3586 3802 ok (non-closed singly connected) (0.0051635397 -0.0068516134 -9.865518e-12) (0.024315742 0.0068497157 0.018663031)
RAD_SHR 7446 7586 ok (non-closed singly connected) (0.014784628 -0.0095592735 0.0065231199) (0.024309277 0.0068509049 0.01864559)
RAD_BLADE_0 6006 6160 ok (non-closed singly connected) (0.005537279 -0.0055899046 -9.865518e-12) (0.023663878 0.0011922848 0.017550802)
BLADE_TIP 2474 2552 ok (non-closed singly connected) (0.016455274 -0.0055899046 0.0064015365) (0.023662441 0.0002629348 0.017535285)
IFC2_UPS_TO_IMP 4402 4536 ok (non-closed singly connected) (0.023330942 -0.0068516134 4.3901804e-19) (0.024315742 0.0068509049 0.0065231199)
IFC1_IMP_TO_UPS 4402 4536 ok (non-closed singly connected) (0.0051635397 -0.0095592735 0.018643549) (0.017605754 -2.2805322e-05 0.018663031)
OUTLET 4402 4536 ok (non-closed singly connected) (0.0051635013 -0.0095609661 0.0489646) (0.017605827 -2.2876245e-05 0.0489646)
PER1_DWS 2728 2835 ok (non-closed singly connected) (0.0051629153 -0.0095661627 0.018645527) (0.014784688 -0.0033455142 0.0489646)
PER2_DWS 2728 2835 ok (non-closed singly connected) (0.0061525657 -0.00010649717 0.018645527) (0.017605839 6.4763128e-06 0.0489646)
HUB_DWS 3124 3240 ok (non-closed singly connected) (0.0051629153 -0.0033464822 0.018645577) (0.0061525676 -2.2805327e-05 0.0489646)
SHROUD_DWS 3124 3240 ok (non-closed singly connected) (0.014780302 -0.0095661627 0.018645525) (0.017605839 -4.8596013e-05 0.0489646)
IFC2_IMP_TO_DWS 4402 4536 ok (non-closed singly connected) (0.0051635397 -0.0095593084 0.018645525) (0.017605824 6.4763128e-06 0.018663211)
Checking geometry...
This is a 3-D mesh
Overall domain bounding box (0.0051629153 -0.0095661627 -9.865518e-12) (0.030186862 0.0085049543 0.0489646)
Mesh (non-empty, non-wedge) directions (1 1 1)
Mesh (non-empty) directions (1 1 1)
Mesh (non-empty, non-wedge) dimensions 3
Boundary openness (-6.3795052e-16 1.6164244e-16 -3.1703713e-16) Threshold = 1e-06 OK.
Max cell openness = 4.7481174e-15 OK.
Max aspect ratio = 248.69674 OK.
Minumum face area = 5.5833299e-12. Maximum face area = 1.0159705e-06. Face area magnitudes OK.
Min volume = 3.7092636e-17. Max volume = 2.1934866e-10. Total volume = 4.3995348e-06. Cell volumes OK.
Mesh non-orthogonality Max: 86.541631 average: 18.373099 Threshold = 70
*Number of severely non-orthogonal faces: 1261.
Non-orthogonality check OK.
Writing 1261 non-orthogonal faces to set nonOrthoFaces
Face pyramids OK.
***Max skewness = 4.3764234, 4 highly skew faces detected Threshold = 4
Writing 4 skew faces to set skewFaces
Min/max edge length = 1.1174641e-06 0.0011549148 OK.
Writing 192 near (closer than 5.7881735e-08 apart) points to set nearPoints
All angles in faces OK.
Face flatness (1 = flat, 0 = butterfly) : average = 0.99997935 min = 0.9442212
All face flatness OK.
Cell determinant (wellposedness) : minimum: 2.3853008e-09 average: 0.98973614
***Cells with small determinant found, number of cells: 19269
Writing 19269 under-determined cells to set underdeterminedCells
Failed 2 mesh checks.
End
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June 24, 2014, 06:40
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#29 | |
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New Member
Join Date: May 2011
Posts: 28
Rep Power: 14 |
Quote:
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June 26, 2014, 02:47
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Turbo Performance Problem
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#30 |
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Senior Member
Join Date: Sep 2013
Location: Bangalore India
Posts: 134
Rep Power: 12 |
Hi,
I have improved the quality of mesh and checked the mesh quality before simulation. It gave Mesh OK message. Now simulation is going on. But i have attached turbo performance code in controlDict as follows. Code:
turboPerformance
{
type turboPerformance;
functionObjectLibs ("libturboPerformance.so");
turbine true; // Turbine mode, (false if Pump)
//
log true; // write data to screen (true/false)
outputControl timeStep; // write data to file (same options as case output)
outputInterval 10; // interval to write data to file
//
inletPatches (INLET); // inlet patches, can be multiple
outletPatches (OUTLET); // outlet patches, can be multiple
patches (RAD_BLADE_0 RAD_HUB RAD_SHR BLADE_TIP PERIODIC1 PERIODIC2 IFC1_IMP_TO_UPS IFC2_UPS_TO_IMP); // rotor/impeller patches, again can be multiple
//
rhoInf 0.3547; // density
CofR (0 0 0); // center of rotation
omega (0 0 1179.3833333333); // Rotational velocity (rad/s)
/*
pName p; //Optional: if p field is not called "p", give a new name here
Uname Uabs; //Optional: if U field is not called "U", give a new name here
phiName phi; //Optional: if phi (flux) field is not called "phi", give a new name here
*/
}
fluidPower
{
type fluidPower;
functionObjectLibs ("libturboPerformance.so");
//
turbine true; // Turbine mode, (false if Pump)
//
log true; // write data to screen (true/false)
outputControl timeStep; // write data to file (same options as case output)
outputInterval 10; // interval to write data to file
//
inletPatches (INLET);
outletPatches (OUTLET);
rhoInf 0.3547;
}
But the values obtained are very strange which are as follows Code:
performance data: Head (m) = -1982.5526 TOmega (W) = 4.3479324 Eff (%) = -5.3890478 Forces = (-0.36608541 0.42663492 -0.39401571) Moments = (-0.0051551442 0.0042789996 0.0036866151) Fluid power output: dEm (W) = -80.680903 Head (m) = -1982.5526 |
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July 7, 2014, 06:20
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Need a paper
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#31 |
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Senior Member
Join Date: Sep 2013
Location: Bangalore India
Posts: 134
Rep Power: 12 |
Hi,
Anybody is having this paper ? Code:
O. Borm et al., Density based navier stokes solver for transonic ows," OpenFoam 6th workshop, 2011. |
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