# Help with a problem running MPPICFoam

 User Name Remember Me Password
 Register Blogs Members List Search Today's Posts Mark Forums Read

 LinkBack Thread Tools Search this Thread Display Modes
 June 5, 2020, 12:47 Help with a problem running MPPICFoam #1 New Member   Kyle Moon Join Date: Apr 2019 Posts: 5 Rep Power: 6 Hi, I am looking for some help troubleshooting a problem that I have when running MPPICFOam. I first started with the cyclone tutorial and then changed the geometry/mesh to a simplified version of my solution, I also ran it with lower then actual boundary conditions. This ran with a small problem that the was easy to correct by adding adjustable time steps with a max Courant number. The problem was that the k.air would become unstable. bounding k.air, min: -1.27685e+10 max: 5.48249e+12 average: 6.19542e+10 And the time step would become really small. Courant Number mean: 0.000995892 max: 0.994049 deltaT = 3.76105e-10 Time = 1.01671 I solved this by decrease the max courant number. Thinking I solved the problem I ran a full scale simulation. I ran into some problems here as well. The first on was the: Cloud: kinematicCloud injector: model1 Added 1000 new parcels GAMG: Solving for kinematicCloud:alpha, Initial residual = 0.973777, Final residual = 2.56743e-16, No Iterations 1 I solved this by changing the Courant number as well. Having run that simulation I changed the geometry a little to see what the effect will be on the particle cloud. Now the simulation doesn't work with the setting of the previous simulation. It seems that the cell volume fraction goes over one and the simulation crashes. This is the final time step from the log: Courant Number mean: 0.0334176 max: 1.68594 deltaT = 0.0001 Time = 1.1791 Evolving kinematicCloud Solving 3-D cloud kinematicCloud Cloud: kinematicCloud injector: model1 Added 500 new parcels GAMG: Solving for kinematicCloud:alpha, Initial residual = 3.97258e-07, Final residual = 3.97258e-07, No Iterations 0 Cloud: kinematicCloud Current number of parcels = 895500 Current mass in system = 14.925 Linear momentum = (-46.7636 1.19096 -129.692) |Linear momentum| = 137.871 Linear kinetic energy = 693.699 Average particle per parcel = 15962.1 Injector model1: - parcels added = 895500 - mass introduced = 14.925 Parcel fate: system (number, mass) - escape = 0, 0 Parcel fate: patch walls (number, mass) - escape = 0, 0 - stick = 0, 0 Parcel fate: patch inlet (number, mass) - escape = 0, 0 - stick = 0, 0 Parcel fate: patch outletLeft (number, mass) - escape = 0, 0 - stick = 0, 0 Parcel fate: patch outletRight (number, mass) - escape = 0, 0 - stick = 0, 0 Parcel fate: patch mealInlet (number, mass) - escape = 0, 0 - stick = 0, 0 Min cell volume fraction = 0 Max cell volume fraction = 1.13689 Min dense number of parcels = 3.00998 PIMPLE: iteration 1 smoothSolver: Solving for U.airx, Initial residual = 0.000278857, Final residual = 3.31328e-07, No Iterations 1 smoothSolver: Solving for U.airy, Initial residual = 0.000180067, Final residual = 2.27856e-07, No Iterations 1 smoothSolver: Solving for U.airz, Initial residual = 0.000107174, Final residual = 1.14479e-07, No Iterations 1 GAMG: Solving for p, Initial residual = 0.143885, Final residual = 0.00120846, No Iterations 2 time step continuity errors : sum local = 4.15175e-08, global = 1.38267e-10, cumulative = 1.45161e-08 GAMG: Solving for p, Initial residual = 0.00607239, Final residual = 9.60646e-07, No Iterations 12 time step continuity errors : sum local = 3.29827e-11, global = 1.07283e-12, cumulative = 1.45172e-08 smoothSolver: Solving for k.air, Initial residual = 9.97073e-05, Final residual = 1.01603e-07, No Iterations 1 bounding k.air, min: -1.53681 max: 263.462 average: 2.57929 ExecutionTime = 46203.4 s ClockTime = 47319 s Courant Number mean: 0.0334176 max: 2.09401 deltaT = 0.0001 Time = 1.1792 Evolving kinematicCloud Solving 3-D cloud kinematicCloud Cloud: kinematicCloud injector: model1 Added 500 new parcels GAMG: Solving for kinematicCloud:alpha, Initial residual = 0.694129, Final residual = 3.6204e-17, No Iterations 1 I have tried changing the fineness of the mesh, as well as the time step size and it still doesn't want to run. It also crashes at the same time in the simulation, it doesn't matter what I do to the time step or mesh size. If anyone has a suggestion on what I should look at to try and fix this problem it will be very helpful. Thanks,

 June 7, 2020, 16:12 #2 New Member   Kyle Moon Join Date: Apr 2019 Posts: 5 Rep Power: 6 Hi, I solved the problem by increasing my parcelsPerSecond by 50%. I think there was an issue with the parcel size and the cell size that might have been causing the cell volume fraction to go over 1.0 and cause it to crash. Farid likes this.

 Thread Tools Search this Thread Search this Thread: Advanced Search Display Modes Linear Mode

 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 OffTrackbacks are Off Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Asghari_M OpenFOAM Programming & Development 1 May 11, 2015 06:13 [waves2Foam] Problem in running Allrun and also setWaveFields ankitchy OpenFOAM Community Contributions 2 March 9, 2015 09:10 Phanipavan STAR-CD 1 September 11, 2013 07:42 dhruv OpenFOAM 3 November 25, 2011 06:06 platopus OpenFOAM Bugs 8 April 15, 2008 08:52

All times are GMT -4. The time now is 06:08.

 Contact Us - CFD Online - Privacy Statement - Top