# Time Step Continuity

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 November 26, 2012, 07:40 Time Step Continuity #1 New Member   Matthias Join Date: Oct 2012 Location: Erlangen Posts: 8 Rep Power: 7 Hi, I am new to OpenFoam and I try to simulate a axisymmetric flow. My result doesn't look very useful in the paraviewer. By solving with the icoFoam-solver I get the following message (here the last time step): Code: ```Time = 0.6 Courant Number mean: 2.23e+34 max: 5.65961e+37 DILUPBiCG: Solving for Ux, Initial residual = 0.998035, Final residual = 6.06503e+07, No Iterations 1001 DILUPBiCG: Solving for Uy, Initial residual = 0.902429, Final residual = 8.16874, No Iterations 1001 DILUPBiCG: Solving for Uz, Initial residual = 0.997655, Final residual = 2.25247, No Iterations 1001 DICPCG: Solving for p, Initial residual = 1, Final residual = 18.6765, No Iterations 1001 time step continuity errors : sum local = 6.55952e+47, global = -8.33417e+31, cumulative = -8.33417e+31 DICPCG: Solving for p, Initial residual = 0.998855, Final residual = 7.59938, No Iterations 1001 time step continuity errors : sum local = 4.59185e+51, global = -4.68485e+35, cumulative = -4.68568e+35 ExecutionTime = 38.21 s ClockTime = 39 s``` Can somebody help me? Thank you!!

 November 27, 2012, 04:48 #2 Senior Member     ATM Join Date: May 2009 Location: United States Posts: 104 Rep Power: 10 Hi, There is a serious problem in your case setup because the Courant number Code: ` Courant Number mean: 2.23e+34 max: 5.65961e+37` Can never , ever be so high. You are not implementing the right BCs. What case are you trying to simulate? Regards, A.T.M hiasl likes this.

 December 2, 2012, 06:45 #3 Member   Zifei Yin Join Date: Sep 2012 Location: Shanghai & Ames Posts: 33 Rep Power: 7 Please do checkMesh before calculation, probably there are some mesh problems. Also, reduce the time-step to see if there is any changes.

 December 3, 2012, 07:03 #4 New Member   Matthias Join Date: Oct 2012 Location: Erlangen Posts: 8 Rep Power: 7 the blockMesh: Code: ```convertToMeters 0.001; vertices ( (0 0 0) // 0 Bottom (88 3.0730 0) // 1 Bottom (88 3.0730 2) // 2 Top (0 0 2) // 3 Top (88 -3.0730 0) // 4 Bottom (88 -3.0730 2) // 5 Top (32.5 -1.134925 2)// 6 Top (32.5 1.134925 2) // 7 Top (32.5 1.134925 0) // 8 Bottom (32.5 -1.134925 0)// 9 Bottom (62.5 -2.1825 0) //10 Bottom (62.5 2.1825 0) //11 Bottom (0 0 1) //12 Mid (32.5 1.134925 1) //13 Mid (32.5 -1.134925 1)//14 Mid (62.5 -2.1825 1) //15 Mid (62.5 2.1825 1) //16 Mid (88 -3.0730 1) //17 Mid (88 3.0730 1) //18 Mid (62.5 2.1825 2) //19 Top (62.5 -2.1825 2) //20 Top ); blocks ( // hex (0 9 8 0 3 6 7 3) (20 20 20) simpleGrading (1 1 1) //wedge // hex (8 9 4 1 7 6 5 2) (20 20 20) simpleGrading (1 1 1) //wholeBlock hex (0 9 8 0 12 14 13 12) (50 50 50) simpleGrading (0.1 1 10) //wedgeBottom 0 hex (12 14 13 12 3 6 7 3) (50 50 50) simpleGrading (0.1 1 0.1) //wedgeTop 1 hex (9 10 11 8 14 15 16 13) (50 50 50) simpleGrading (10 1 10) // midBottom 2 hex (14 15 16 13 6 20 19 7) (50 50 50) simpleGrading (10 1 0.1) // midTop 3 hex (10 4 1 11 15 17 18 16) (50 50 50) simpleGrading (0.1 1 10) // outBottom 4 hex (15 17 18 16 20 5 2 19) (50 50 50) simpleGrading (0.1 1 0.1)// outTop 5 ); edges ( ); boundary ( front { type wedge; faces ( (0 8 13 12) (12 13 7 3) ); } back { type wedge; faces ( (0 12 14 9) (12 3 6 14) ); } tankWall { type wall; faces ( (1 4 17 18) (18 17 5 2) ); } bottomWall { type wall; faces ( (0 9 8 0) (8 9 10 11) (11 10 4 1) ); } rotatingPlate { type wall; faces ( (3 7 6 3) ); } openFluid { type patch; faces ( (7 19 20 6) (19 2 5 20) (9 14 15 10) (10 15 17 4) (14 6 20 15) (15 20 5 17) (11 1 18 16) (8 11 16 13) (16 18 2 19) (13 16 19 7) ); } axis { type empty; faces ( (0 12 12 0) (12 3 3 12) ); } ); mergePatchPairs ( );``` checkMesh tells me this: Code: ```Build : 2.1.1-221db2718bbb Exec : checkMesh Date : Dec 03 2012 Time : 12:00:30 Host : "lstma243" PID : 25757 Case : /tmp/OpenFOAM/matthias-2.1.1/tutorials/incompressible/icoFoam/cavity nProcs : 1 sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE). fileModificationChecking : Monitoring run-time modified files using timeStampMas ter allowSystemOperations : Disallowing user-supplied system call operations // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // Create time Create polyMesh for time = 0 Time = 0 Mesh stats points: 772751 faces: 2272500 internal faces: 2222500 cells: 750000 boundary patches: 7 point zones: 0 face zones: 0 cell zones: 0 Overall number of cells of each type: hexahedra: 745000 prisms: 5000 wedges: 0 pyramids: 0 tet wedges: 0 tetrahedra: 0 polyhedra: 0 Checking topology... Boundary definition OK. Cell to face addressing OK. Point usage OK. Upper triangular ordering OK. Face vertices OK. Number of regions: 1 (OK). Checking patch topology for multiply connected surfaces ... Patch Faces Points Surface topology front 5000 5151 ok (non-closed singly connected) back 5000 5151 ok (non-closed singly connected) tankWall 5000 5151 ok (non-closed singly connected) bottomWall 7500 7651 ok (non-closed singly connected) rotatingPlate 2500 2551 ok (non-closed singly connected) openFluid 25000 25351 ok (non-closed singly connected) axis 0 0 ok (empty) Checking geometry... Overall domain bounding box (0 -0.003073 0) (0.088 0.003073 0.002) Mesh (non-empty, non-wedge) directions (1 0 1) Mesh (non-empty) directions (1 1 1) Wedge front with angle 2 degrees Wedge back with angle 2 degrees ***Number of edges not aligned with or perpendicular to non-empty directions: 7 47400 <

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