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 April 28, 2005, 05:36 Well, thanks Tommaso, but now #21 Member   Ervin Adorean Join Date: Mar 2009 Posts: 72 Rep Power: 10 Well, thanks Tommaso, but now I'm confused. > 'maxDeltaT in an engine simulation is the MAXIMUM CRANK ANGLE (and not the TIME STEP) and it should be kept around 0.1' What MAXIMUM CRANK ANGLE is maxDeltaT? In dieselEngineFoam and engineFoam time=CAD, right? Can you please explain it in more detail? Ervin

 May 2, 2005, 04:27 Hello, I would very much ap #22 Member   Ervin Adorean Join Date: Mar 2009 Posts: 72 Rep Power: 10 Hello, I would very much appreciate some guidelines for using 'dieselEngineFoam'. Is it OK to define the piston, liner and cylinderhead temp. b.c. as fixedValue? And how is that light speed-like value of "Average Velocity for injector 0: 5.63034e+06 m/s, injection pressure = 1200 bar" calculated? Does this need to be calculated, even if injection doesn't exist at that time? For a calculation starting at -180 CAD and ending at -10 CAD, the injection beginning at -4.4 CAD I always get divergence sooner or later, because of a high Courant number. Which is the best way of keeping the Courant number low? Thanks! Ervin

 May 2, 2005, 11:27 Now even with a low Courant nu #23 Member   Ervin Adorean Join Date: Mar 2009 Posts: 72 Rep Power: 10 Now even with a low Courant number, I've got this error message: Max Courant Number = 0.0900482 deltaT = 2.57864e-14 Crank angle = -178.087 CA-deg deltaZ = 6.93889e-15 void fvMesh::makePhi() : creating zero flux field tmp polyMesh::movePoints(const pointField&) : Moving points for time -0.0197875 index 183 bool primitiveMesh::checkMeshMotion(const pointField& newPoints, const bool report) const: checking mesh motion Min volume = 4.03647e-11. Total volume = 0.000243926. Cell volumes OK. Min area = 3.42112e-08. Face areas OK. Pyramid volumes OK. Non-orthogonality check OK. Mesh motion check OK. void fvMesh::makeCf() : assembling face centres void fvMesh::makeC() : assembling cell centres void fvMesh::makeSf() : assembling face areas void fvMesh::makeMagSf() : assembling mag face areas clearance: 0.155971 Piston speed = 0.269091 m/s volume continuity errors : sum local = 1.63264e-15, global = 8.5799e-19 Solving chemistry BICCG: Solving for Ux, Initial residual = 0.604385, Final residual = 2.0787e-07, No Iterations 17 BICCG: Solving for Uy, Initial residual = 0.351684, Final residual = 7.86904e-07, No Iterations 18 BICCG: Solving for Uz, Initial residual = 0.999143, Final residual = 5.99763e-07, No Iterations 36 BICCG: Solving for h, Initial residual = 1, Final residual = 5.14966e-07, No Iterations 39 --> FOAM FATAL ERROR : attempt to use janafThermo out of temperature range 200 -> 5000; T = 61502.9 Function: janafThermo::checkT(const scalar T) const in file: /home/ervin/OpenFOAM/OpenFOAM-1.1/src/thermophysicalModels/specie/lnInclude/jana fThermoI.H at line: 73. FOAM aborting Anybody has a hint? What is wrong in my case setup?

 July 10, 2007, 00:41 Hello, I'm new to C++. In #24 atsushi Guest   Posts: n/a Hello, I'm new to C++. In dieselEngineFoam, What is the relationship between "adjustTimeStep" and "maxDeltaT"? Please teach me. thank you. Atsushi

 July 10, 2007, 01:31 Hi, These parameters are in #25 New Member   Masato Otsuki Join Date: Mar 2009 Location: Tokyo, Japan Posts: 26 Rep Power: 10 Hi, These parameters are input at: \$FOAM_SRC/src/finiteVolume/lnInclude/readTimeControls.H And used at: \$FOAM_SRC/finiteVolume/lnInclude/setDeltaT.H Masato

 July 10, 2007, 01:34 sorry, \$FOAM_SRC/src/finite #26 New Member   Masato Otsuki Join Date: Mar 2009 Location: Tokyo, Japan Posts: 26 Rep Power: 10 sorry, \$FOAM_SRC/src/finiteVolume/lnInclude/readTimeControls.H --> \$FOAM_SRC/finiteVolume/lnInclude/readTimeControls.H Masato

 July 10, 2007, 02:16 Thanks, Masato. Atsushi #27 atsushi Guest   Posts: n/a Thanks, Masato. Atsushi

 September 14, 2007, 01:30 Hi, What is the unit of "dQ #28 atsushi Guest   Posts: n/a Hi, What is the unit of "dQ"? [J/θ]? [J/s}? I want to calculate ROHR per clank angle. thanks. Atsu

 September 14, 2007, 03:56 hi, look in the createfield #29 Senior Member   Stephan Gerber Join Date: Mar 2009 Location: Germany Posts: 118 Rep Power: 10 hi, look in the createfields.h-file- this file creates dQ with unit dimensionSet(1,-3,-1,0,0,0,0). regards stephan

 October 8, 2007, 02:18 hi, Stephan I checked dQ di #30 atsushi Guest   Posts: n/a hi, Stephan I checked dQ dimensionSet(1,-3,-1,0,0,0,0)in the createfields.h-file-. It's not heat release rate. dQ unit is "density per second"...?? If the unit is so, dQ has no relation to heat release rate. I misunderstand that "dQ = heat release rate". Am I right? Thanks, Atsu

 October 8, 2007, 02:26 check hEqn.H, the term is a #31 Super Moderator     Niklas Nordin Join Date: Mar 2009 Location: Stockholm, Sweden Posts: 693 Rep Power: 22 check hEqn.H, the term is a bit misleading since its divided by cp.

 October 9, 2007, 21:27 hi,Niklas I checked hEqn.H. #32 atsushi Guest   Posts: n/a hi,Niklas I checked hEqn.H. It seems that "[dQ]=[h][RR]/[Cp]" If, [h]=J/kg [RR]=kg/m3/s [Cp]=J/kg/K then, the unit of dQ is shown by [dQ]= kg.K/m3/s =[1 -3 -1 1 0 0 0] ...What is this unit?? I'm new to C++,and my explanation may wrong. Please teach me the meaning of dQ unit. Thanks, Atsu

 November 19, 2007, 09:07 Hi, I was solving a case usin #33 New Member   N S Prasad Join Date: Mar 2009 Posts: 15 Rep Power: 10 Hi, I was solving a case using engine foam. the case solved till CA -27.6 Degs and then gave the following error. Courant Number mean: 0.00327122 max: 0.200576 deltaT = 5.94218e-06 Crank angle = -27.6924 CA-deg deltaZ = 6.52008e-05 clearance: 0.0190537 Piston speed = 10.9725 m/s diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 #0 Foam::error::printStack(Foam:stream&) #1 Foam::sigFpe::sigFpeHandler(int) #2 Uninterpreted: [0xfb1420] #3 void Foam::fvc::surfaceIntegrate >(Foam::Field >&, Foam::GeometricField, Foam::fvPatchField, Foam::surfaceMesh> const&) #4 Foam::tmp, Foam::fvPatchField, Foam::volMesh> > Foam::fvc::surfaceIntegrate >(Foam::GeometricField, Foam::fvPatchField, Foam::surfaceMesh> const&) #5 Foam::tmp, Foam::fvPatchField, Foam::volMesh> > Foam::fvc::surfaceIntegrate >(Foam::tmp, Foam::fvPatchField, Foam::surfaceMesh> > const&) #6 Foam::fv::gaussDivScheme >::fvcDiv(Foam::GeometricField, Foam::fvPatchField, Foam::volMesh> const&) #7 Foam::tmp, Foam::Tensor >::type, Foam::fvPatchField, Foam::volMesh> > Foam::fvc::div >(Foam::GeometricField, Foam::fvPatchField, Foam::volMesh> const&, Foam::word const&) #8 Foam::tmp, Foam::Tensor >::type, Foam::fvPatchField, Foam::volMesh> > Foam::fvc::div >(Foam::GeometricField, Foam::fvPatchField, Foam::volMesh> const&) #9 Foam::tmp, Foam::Tensor >::type, Foam::fvPatchField, Foam::volMesh> > Foam::fvc::div >(Foam::tmp, Foam::fvPatchField, Foam::volMesh> > const&) #10 Foam::compressible::turbulenceModels::kEpsilon::di vRhoR(Foam::GeometricField, Foam::fvPatchField, Foam::volMesh>&) const #11 main #12 __libc_start_main #13 __gxx_personality_v0 at ../sysdeps/i386/elf/start.S:122 Floating point exception Can any one point out how i can resolve the same? Regards,

 November 20, 2007, 00:27 Ok. I was using a hybrid mesh #34 New Member   N S Prasad Join Date: Mar 2009 Posts: 15 Rep Power: 10 Ok. I was using a hybrid mesh tet + hex. i put in a little more effort and changed the entire mesh to hex. and the problem has been solved. i would like to put the sim video here. but dont have a clue as to how .. (yes u can use tet mesh for engine mesh:-) urs, prasad.

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