- **OpenFOAM Running, Solving & CFD**
(*http://www.cfd-online.com/Forums/openfoam-solving/*)

- - **Low Mach number Compressible jet flow using LES**
(*http://www.cfd-online.com/Forums/openfoam-solving/59372-low-mach-number-compressible-jet-flow-using-les.html*)

Hello,
Has anybody used OpeHello,
Has anybody used OpenFOAM to model a low-Mach number compressible jet (reacting non/reacting) flow with LES ?? I am trying to simulate a nonreacting compressible jet flow using Coodles solver and have not been able to get a reasonable flow field. Looks like, the pressure waves in my computational domain are destroying the solution. I am using waveTransmissive pressure boundary at the outlet. I tried playing with the lInf parameter but that didn't help. Also, I am not familiar with what constitutes a reasonable initial condition for this compressible jet flow case. I am using an expanding jet as my initial condition. Any comments concerning above will be of great help !! Regards, Ankur |

Hi Ankur,
we have had some Hi Ankur,
we have had some luck working on non-reactive gas expansions into vacuum with Mach numbers up to 0.7 or so using sonicFoam. We used pressureTransmissiveOutlet at the outlet. As for the initial conditions, we found that starting with a uniform high pressure, and slowly "pumping down" the volume allowed convergence. Hope this helps, Jacques |

Hi!
I have been running for aHi!
I have been running for a Mach=0.3 jet using the Xoodles solver. The jet is laminar at the inlet and turns turbulent about 4D downstream. The setup is a round tube with walls and open outflow end. The tube is 32D long and 8D wide. The simulations were carried out using the same discretization schemes as in the Xoodles pitz daily tutorial but by choosing for the convection discretization the linearLimitedV 0 scheme. This provides best accuracy according to the manual. I believe this since choosing 1 does not give good results. I guess the 0 choice is not central differencing but there is still some amount of dissipation added to the system. I'm doing implicit LES so the Smagorinsky sgs model is chosen and the constants set to zero. I use the fixedValue BC for the pressure at the end of the domain since I extend the domain far from the inlet (32D). My experience is that easily, there are some kind of oscillations that seem to be developed at the outlet if the outlet is not extended far away enough. I hope this helps, please ask more if you are interested. And here is an image attached (if my browser supports uploading): http://www.cfd-online.com/OpenFOAM_D...ges/1/5535.jpg. -Ville |

Hey Ville and Jacques,
ThanHey Ville and Jacques,
Thanks for your response. Will update you people with the results of my run. I am simulating a low Mach variable density jet using Coodles with pressure transmissive boundaries at the outlet and the peripheral surface of my cylinder geometry. Regards, Ankur |

Hello,
I am trying to simulHello,
I am trying to simulate a co-axial annular jet flow into a cylindrical pipe using coodles solver, where I have not been able to get a stable run. My runs are getting aborted with a sudden increase in the maximum Courant number finally resulting in an error message about exceeding maximum of iterations while calculating temperature. The residual transcript is attached here: ----------------------------------------- Time = 0.0368 Courant Number mean: 0.00493845040729 max: 0.429119452441 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 DILUPBiCG: Solving for Ux, Initial residual = 0.00844410758944, Final residual = 4.66454426171e-06, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 0.00846817925502, Final residual = 4.99792349866e-06, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 0.0013625406798, Final residual = 8.85489123382e-07, No Iterations 1 DILUPBiCG: Solving for h, Initial residual = 0.00172847114208, Final residual = 7.71266079232e-09, No Iterations 2 DICPCG: Solving for p, Initial residual = 0.0415841917657, Final residual = 7.49203039837e-07, No Iterations 25 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors : sum local = 4.83155467319e-10, global = 4.63888325046e-11, cumulative = -6.42437470136e-08 DILUPBiCG: Solving for h, Initial residual = 2.69584213671e-05, Final residual = 5.51469817127e-08, No Iterations 1 DICPCG: Solving for p, Initial residual = 0.00644210288592, Final residual = 7.89151406872e-07, No Iterations 22 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors : sum local = 9.21918837415e-10, global = -3.43593067706e-11, cumulative = -6.42781063203e-08 ExecutionTime = 20403.47 s ClockTime = 20641 s Time = 0.03682 Courant Number mean: 0.00494281068601 max: 0.442473073516 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 DILUPBiCG: Solving for Ux, Initial residual = 0.00799533478168, Final residual = 4.51907293252e-06, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 0.00801281540665, Final residual = 4.71147001509e-06, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 0.00135955162134, Final residual = 8.8304809434e-07, No Iterations 1 DILUPBiCG: Solving for h, Initial residual = 0.00173322624585, Final residual = 8.50065129903e-09, No Iterations 2 DICPCG: Solving for p, Initial residual = 0.0493330030561, Final residual = 9.04114322406e-07, No Iterations 25 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors : sum local = 5.40755918166e-10, global = 5.38300132589e-11, cumulative = -6.42242763071e-08 DILUPBiCG: Solving for h, Initial residual = 2.58833370413e-05, Final residual = 6.95390874326e-08, No Iterations 1 DICPCG: Solving for p, Initial residual = 0.00628313568556, Final residual = 9.66627641829e-07, No Iterations 22 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors : sum local = 1.16907836236e-09, global = -5.44546061308e-11, cumulative = -6.42787309132e-08 ExecutionTime = 20414.86 s ClockTime = 20652 s Time = 0.03684 Courant Number mean: 0.00494559475368 max: 0.4713915416 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 DILUPBiCG: Solving for Ux, Initial residual = 0.00742280584779, Final residual = 4.38613346232e-06, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 0.00742625329947, Final residual = 4.43719748206e-06, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 0.00135999558636, Final residual = 8.82383962128e-07, No Iterations 1 DILUPBiCG: Solving for h, Initial residual = 0.00173962165641, Final residual = 1.06264541946e-08, No Iterations 2 DICPCG: Solving for p, Initial residual = 0.0571073390535, Final residual = 6.55054566033e-07, No Iterations 26 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors : sum local = 4.09309772837e-10, global = 4.8162743372e-11, cumulative = -6.42305681698e-08 DILUPBiCG: Solving for h, Initial residual = 2.51646487615e-05, Final residual = 5.33933235498e-08, No Iterations 1 DICPCG: Solving for p, Initial residual = 0.00625896355778, Final residual = 8.47352154576e-07, No Iterations 23 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors : sum local = 1.03864436609e-09, global = -6.79706385552e-11, cumulative = -6.42985388084e-08 ExecutionTime = 20426.44 s ClockTime = 20664 s Time = 0.03686 Courant Number mean: 0.0049465222409 max: 0.515848688524 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 DILUPBiCG: Solving for Ux, Initial residual = 0.00721729867396, Final residual = 4.74418750241e-06, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 0.00719419756934, Final residual = 4.57611753738e-06, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 0.00136136060364, Final residual = 8.86968650621e-07, No Iterations 1 DILUPBiCG: Solving for h, Initial residual = 0.00174447321572, Final residual = 9.90147542931e-07, No Iterations 1 DICPCG: Solving for p, Initial residual = 0.0625252896496, Final residual = 8.78262200939e-07, No Iterations 26 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors : sum local = 6.10375720828e-10, global = 7.63717320388e-11, cumulative = -6.42221670764e-08 DILUPBiCG: Solving for h, Initial residual = 2.61415047737e-05, Final residual = 2.90315831642e-08, No Iterations 1 DICPCG: Solving for p, Initial residual = 0.00690753768077, Final residual = 8.13505196251e-07, No Iterations 25 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors : sum local = 1.04006941608e-09, global = -1.28577132884e-10, cumulative = -6.43507442092e-08 ExecutionTime = 20437.94 s ClockTime = 20675 s Time = 0.03688 Courant Number mean: 0.00494564080085 max: 0.647052955746 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 DILUPBiCG: Solving for Ux, Initial residual = 0.00732107466716, Final residual = 4.63592222575e-06, No Iterations 2 DILUPBiCG: Solving for Uy, Initial residual = 0.00729833336673, Final residual = 5.22807373014e-07, No Iterations 2 DILUPBiCG: Solving for Uz, Initial residual = 0.00136284818003, Final residual = 9.67238589607e-07, No Iterations 1 DILUPBiCG: Solving for h, Initial residual = 0.00174708577786, Final residual = 1.17395087064e-07, No Iterations 2 DICPCG: Solving for p, Initial residual = 0.0650790363107, Final residual = 8.42601804973e-07, No Iterations 27 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors : sum local = 7.23975369161e-10, global = 7.7405542146e-11, cumulative = -6.42733386671e-08 DILUPBiCG: Solving for h, Initial residual = 2.9339801583e-05, Final residual = 8.9252754109e-08, No Iterations 1 DICPCG: Solving for p, Initial residual = 0.0108816829259, Final residual = 9.28479404945e-07, No Iterations 28 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors : sum local = 1.19155561929e-09, global = -9.66552632455e-11, cumulative = -6.43699939303e-08 ExecutionTime = 20450.09 s ClockTime = 20687 s Time = 0.0369 Courant Number mean: 0.004947400605 max: 2.5520876727 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 DILUPBiCG: Solving for Ux, Initial residual = 0.00769358118698, Final residual = 6.30975426212e-08, No Iterations 4 DILUPBiCG: Solving for Uy, Initial residual = 0.00766033122292, Final residual = 5.41766047e-07, No Iterations 4 DILUPBiCG: Solving for Uz, Initial residual = 0.00137421028602, Final residual = 3.7420370251e-06, No Iterations 1 DILUPBiCG: Solving for h, Initial residual = 0.00175403676822, Final residual = 8.07069641363e-08, No Iterations 5 DICPCG: Solving for p, Initial residual = 0.0705044419196, Final residual = 8.38702133937e-07, No Iterations 30 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors : sum local = 9.17686169978e-10, global = 6.34569299505e-11, cumulative = -6.43065370004e-08 DILUPBiCG: Solving for h, Initial residual = 5.12926280615e-05, Final residual = 3.08699829546e-07, No Iterations 3 DICPCG: Solving for p, Initial residual = 0.380518530765, Final residual = 8.7633895652e-07, No Iterations 33 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors : sum local = 2.07862007257e-09, global = -1.18501136325e-10, cumulative = -6.44250381367e-08 ExecutionTime = 20463.93 s ClockTime = 20701 s Time = 0.03692 Courant Number mean: 0.00515483975594 max: 37.9427998808 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 DILUPBiCG: Solving for Ux, Initial residual = 0.016508981307, Final residual = 4.05477015535e-06, No Iterations 22 DILUPBiCG: Solving for Uy, Initial residual = 0.0148259729626, Final residual = 2.8579679618e-06, No Iterations 22 DILUPBiCG: Solving for Uz, Initial residual = 0.00168636892948, Final residual = 7.75156213696e-06, No Iterations 16 DILUPBiCG: Solving for h, Initial residual = 0.00194544082971, Final residual = 4.0102103118e-07, No Iterations 22 DICPCG: Solving for p, Initial residual = 0.260288630976, Final residual = 6.18861702486e-07, No Iterations 51 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors : sum local = 6.18968759687e-09, global = 4.51533316275e-10, cumulative = -6.39735048204e-08 DILUPBiCG: Solving for h, Initial residual = 0.00740305259218, Final residual = 7.8399331097e-07, No Iterations 153 [0] [0] [0] --> FOAM FATAL ERROR : Maximum number of iterations exceeded#0 Foam::error::printStack(Foam:http://www.cfd-online.com/OpenFOAM_D...part/proud.gifstream&) in "/home/axg330/OpenFOAM/OpenFOAM-1.4.1/lib/linux64GccDPOpt/libOpenFOAM.so" #1 Foam::error::abort() in "/home/axg330/OpenFOAM/OpenFOAM-1.4.1/lib/linux64GccDPOpt/libOpenFOAM.so" #2 Foam::hThermo<foam::puremixture<foam::consttranspo rt<foam::speciethermo<foam::hc onstthermo<foam::perfectgas> > > > >::calculate() in "/home/axg330/OpenFOAM/OpenFOAM-1.4.1/lib/linux64GccDPOpt/libbasicThermophysical Models.so" #3 Foam::hThermo<foam::puremixture<foam::consttranspo rt<foam::speciethermo<foam::hc onstthermo<foam::perfectgas> > > > >::correct() in "/home/axg330/OpenFOAM/OpenFOAM-1.4.1/lib/linux64GccDPOpt/libbasicThermophysical Models.so" #4 main in "/home/axg330/OpenFOAM/OpenFOAM-1.4.1/applications/bin/linux64GccDPOpt/coodles" #5 __libc_start_main in "/lib64/tls/libc.so.6" #6 Foam::regIOobject::readIfModified() in "/home/axg330/OpenFOAM/OpenFOAM-1.4.1/applications/bin/linux64GccDPOpt/coodles" [0] [0] [0] From function specieThermo<thermo>::T(scalar f, scalar T0, scalar (specieThermo<thermo>::*F)(const scalar) const, scalar (specieThermo<thermo>::*dFdT)(const scalar) const) const [0] in file /home/dm2/henry/OpenFOAM/OpenFOAM-1.4.1/src/thermophysicalModels/specie/lnInclud e/specieThermoI.H at line 83. [0] FOAM parallel run aborting [0] ------------------------------------- The initial maximum Courant number for my runs was 0.1. I also tried runs with 0.2. The solver settings I used are the default settings of the coodles tutorial. I also tried using filterdLinear and upwind phi 1.0 for div(phi,u) but that didn't help. I also noticed that the temperature in the computational domain is not bounded and is getting as low as 250 K. That is much before the run got crashed. Just before the run got aborted, the lowest temperature was about 160 K. I also tried using nonorthogonal correctors but that didn't help either. Here is my checkMesh summary: ------------------------ Checking geometry... Domain bounding box: (-0.09999330401 -0.09999377417 0) (0.1 0.09996764146 1.5) Boundary openness (5.05169947962e-16 -2.27942866464e-17 2.68506201545e-18) OK. Max cell openness = 4.83278985275e-16 OK. Max aspect ratio = 45.8026383974 OK. Minumum face area = 3.90625e-07. Maximum face area = 0.000217542727582. Face area magnitudes OK. Min volume = 1.69914629883e-09. Max volume = 3.99078743124e-07. Total volume = 0.0470439397189. Cell volumes OK. Mesh non-orthogonality Max: 38.1691532162 average: 3.61609921545 Non-orthogonality check OK. Face pyramids OK. Max skewness = 0.723087292917 OK. Min/max edge length = 0.000625 0.0191617798286 OK. All angles in faces OK. Face flatness (1 = flat, 0 = butterfly) : average = 0.999999995457 min = 0.999996854308 All face flatness OK. Mesh OK. ------------------------ I have not been able to troubleshoot the problem here. Any suggestions would be highly appreciated. I would be happy to provide more information on my case set-up. Thanks! Regards, Ankur |

Ankur,
I too have had the eAnkur,
I too have had the exact same problem your describing. I can only get my simulation to run 3 time steps though. I am beginning to think that its due to what Ville mentioned, the outlet being too close to my inlet. When I have time I will try and rerun the simulation with a lot more distance in between the two and let you know if it fixes things. Best of luck to you, Conn |

Papers Needed for BenchmarkingHi Guys
I need your help, Please can anyone suggest some good papers which have benchmark results for Plane compressible Jet . I am using Open foam as well as my own code to carry out my simulations . Many Thanks Reagards Turbojet |

jet simulation using LESHello,
I'm ran several simulations of compressible JET M=0.9 Re=6e4 . I was wondering about some stuff: 1. I'm comparing the results to some papers and I see different domain sizes - 5D in r direction and 10D in x direction. other papers use 8D in r and 30D in x - whats more correct? 2. what Bc should i use - it is an isothermal jet - I'm adding the files - are they correct? 3.in LES simulation, does watching the residuals give me something or not - Im plotting them and after a while they stay the same- good or bad - can residuals say anything about convergence in LES? Until now Im watching the U in several places for the run of the simulation using probe. but the results are confusing. 4. do I have to include sponge zone at the end of my mesh? 5. my Pe=20000 - is very high - is it a problem- I dont want a very fine mesh for now. my Files: T: -------------- imensions [0 0 0 1 0 0 0]; internalField uniform 298; boundaryField { inl1 { type fixedValue; value uniform 298; } out { type zeroGradient; } inl2 { type fixedValue; value uniform 298; } side { type totalTemperature; value uniform 298; T0 uniform 298; U U; phi phi; rho none; psi psi; gamma 1.4; } } U ----------- internalField uniform (0 0 0); boundaryField { inl1 { type groovyBC; variables "random_var=(0.5-average(rand()))*33;An=(0.04+random_var*0.0001);St =0.4+random_var*0.00085;phi=pi/3+random_var*0.00085;psi=pi/4+random_var*0.00085;theta=atan(pos().y/pos ().x);u_0=311.4;r_0=0.0016;r=pow(pow(pos().x,2)+po w(pos().y,2),0.5);del1=2*An*cos(St*u_0*time()/(2*r_0)+phi)*cos(1*theta+psi);del2=2*An*cos(St*u_0 *time()/(2*r_0)+phi)*cos(2*theta+psi);del3=2*An*cos(St*u_0 *time()/(2*r_0)+phi)*cos(3*theta+psi);del=20+del1+del2+del 3;u_new=u_0*(0.5-0.5*tanh(del*((r/r_0)-(r_0/r))));"; valueExpression "vector(0,0,u_new)"; value uniform (0 0 311.4); } out { type inletOutlet; inletValue uniform (0 0 0); value uniform (0 0 0); } inl2 { type fixedValue; value uniform (0 0 0); } side { //type zeroGradient; type inletOutlet; inletValue uniform (0 0 0); value uniform (0 0 0); } } // ************************************************** *********************** // P /*--------------------------------*- C++ -*----------------------------------*\ | ========= | | // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [1 -1 -2 0 0 0 0]; internalField uniform 101325; boundaryField { inl1 { type fixedValue; value uniform 101325; } inl2 { type zeroGradient; } out { type waveTransmissive; field p; phi phi; rho rho; psi psi; gamma 1.4; fieldInf 101325; lInf 0.05; value uniform 101325; } side { type waveTransmissive; field p; phi phi; rho rho; psi psi; gamma 1.4; fieldInf 101325; //lInf 0.012; lInf 0.05; value uniform 101325; } } // ************************************************** *********************** // |

All times are GMT -4. The time now is 15:00. |