
[Sponsors] 
August 26, 2013, 01:13 
Rapidly decreasing deltaT for interDyMFoam

#1 
Member
Christian Butcher
Join Date: Jul 2013
Location: Japan
Posts: 84
Rep Power: 4 
Hey,
So I'm currently running a parallel (although this also happens in serial) case using interDyMFoam to dynamically refine my mesh. Ignoring the likely issues with restriction on where I can decompose my mesh to avoid horrible load balancing, the case happily runs for a few iterations, including mesh refinement. After a little while however (around 170s clocktime), the deltaT value starts dropping alarmingly (before this point it is around 10^6, which is expected, but drops approximately an order of magnitude each iteration beyond this point), and then timePrecision is increased to compensate for presumably the data being otherwise labelled at the same time. I am using the adjustableRunTime setup with Courant values limiting the time steps, but the Courant values being output are not equal (or even particularly close to) the limits I have set (0.75 for maxCo, 3 for maxAlphaCo, with maxDeltaT at 1). If anyone can suggest why my case suddenly goes a little crazy, I would appreciate the help. I have attached the output of the data run and have listed below a smaller section of the output. The first file has the relevant sections (I think) in, but I also attached the second half in case the exit messages are important. statLog.txt.gz statLog2.txt.gz Code:
Interface Courant Number mean: 4.10359e10 max: 0.0069883269 Courant Number mean: 1.4039533e07 max: 1.894693 deltaT = 1.7523542e15 Time = 0.002081566360261 Selected 0 cells for refinement out of 97364. Selected 25 split points out of a possible 10256. Unrefined from 97364 to 97189 cells. Execution time for mesh.update() = 0.28 s time step continuity errors : sum local = 7.3659824e09, global = 2.3019959e14, cumulative = 0.0021294309 GAMGPCG: Solving for pcorr, Initial residual = 1, Final residual = 7.7189268e05, No Iterations 25 time step continuity errors : sum local = 5.6857479e13, global = 3.0683831e14, cumulative = 0.0021294309 > FOAM Warning : From function Time::operator++() in file db/Time/Time.C at line 1029 Increased the timePrecision from 13 to 14 to distinguish between timeNames at time 0.0020815664 MULES: Solving for alpha1 Phase1 volume fraction = 0.89999969 Min(alpha1) = 1.1350829e22 Max(alpha1) = 1.0000562 MULES: Solving for alpha1 Phase1 volume fraction = 0.89999969 Min(alpha1) = 2.2336362e22 Max(alpha1) = 1.0000562 MULES: Solving for alpha1 Phase1 volume fraction = 0.89999969 Min(alpha1) = 3.3413735e23 Max(alpha1) = 1.0000562 GAMG: Solving for p_rgh, Initial residual = 0.23603412, Final residual = 0.0092550713, No Iterations 4 time step continuity errors : sum local = 1.2120614e09, global = 1.2161317e11, cumulative = 0.0021294309 GAMG: Solving for p_rgh, Initial residual = 0.27790866, Final residual = 0.010788375, No Iterations 5 time step continuity errors : sum local = 1.4657257e09, global = 7.3197851e13, cumulative = 0.0021294309 GAMGPCG: Solving for p_rgh, Initial residual = 0.2120555, Final residual = 5.3478591e06, No Iterations 21 time step continuity errors : sum local = 1.2998473e12, global = 3.3009001e14, cumulative = 0.0021294309 ExecutionTime = 191.1 s ClockTime = 192 s Interface Courant Number mean: 1.2856088e10 max: 0.0018052402 Courant Number mean: 5.0710819e08 max: 0.29595013 deltaT = 2.102825e15 Time = 0.0020815663602635 Selected 25 cells for refinement out of 97189. Refined from 97189 to 97364 cells. Selected 0 split points out of a possible 10256. Execution time for mesh.update() = 0.28 s time step continuity errors : sum local = 7.6474471e09, global = 3.9610802e14, cumulative = 0.0021294309 GAMGPCG: Solving for pcorr, Initial residual = 1, Final residual = 9.1571304e05, No Iterations 18 time step continuity errors : sum local = 7.0028671e13, global = 9.141037e14, cumulative = 0.0021294309 MULES: Solving for alpha1 Phase1 volume fraction = 0.89999969 Min(alpha1) = 9.037548e23 Max(alpha1) = 1.0000562 MULES: Solving for alpha1 Phase1 volume fraction = 0.89999969 Min(alpha1) = 3.5017732e22 Max(alpha1) = 1.0000562 MULES: Solving for alpha1 Phase1 volume fraction = 0.89999969 Min(alpha1) = 2.4070177e22 Max(alpha1) = 1.0000562 GAMG: Solving for p_rgh, Initial residual = 0.17774109, Final residual = 0.0088413556, No Iterations 3 time step continuity errors : sum local = 6.5470445e09, global = 2.6478718e11, cumulative = 0.0021294309 GAMG: Solving for p_rgh, Initial residual = 0.16833738, Final residual = 0.0056375979, No Iterations 4 time step continuity errors : sum local = 4.4154238e09, global = 1.4618546e11, cumulative = 0.0021294309 GAMGPCG: Solving for p_rgh, Initial residual = 0.27444178, Final residual = 5.3881467e06, No Iterations 21 time step continuity errors : sum local = 3.3351473e12, global = 5.6207951e14, cumulative = 0.0021294309 ExecutionTime = 192.2 s ClockTime = 193 s Interface Courant Number mean: 4.1342592e10 max: 0.0070762091 Courant Number mean: 1.417313e07 max: 1.9252826 deltaT = 8.191622e16 Time = 0.0020815663602643 Selected 0 cells for refinement out of 97364. Selected 25 split points out of a possible 10256. Unrefined from 97364 to 97189 cells. Execution time for mesh.update() = 0.29 s time step continuity errors : sum local = 7.3543405e09, global = 2.1895987e14, cumulative = 0.0021294309 GAMGPCG: Solving for pcorr, Initial residual = 1, Final residual = 7.7400147e05, No Iterations 25 time step continuity errors : sum local = 5.6922704e13, global = 3.0784214e14, cumulative = 0.0021294309 MULES: Solving for alpha1 Phase1 volume fraction = 0.89999969 Min(alpha1) = 1.7487261e23 Max(alpha1) = 1.0000562 MULES: Solving for alpha1 Phase1 volume fraction = 0.89999969 Min(alpha1) = 7.6284817e23 Max(alpha1) = 1.0000562 MULES: Solving for alpha1 Phase1 volume fraction = 0.89999969 Min(alpha1) = 3.5465846e23 Max(alpha1) = 1.0000561 GAMG: Solving for p_rgh, Initial residual = 0.23653799, Final residual = 0.0092471198, No Iterations 4 time step continuity errors : sum local = 1.1919742e09, global = 1.1890053e11, cumulative = 0.0021294309 GAMG: Solving for p_rgh, Initial residual = 0.27559742, Final residual = 0.010717895, No Iterations 5 time step continuity errors : sum local = 1.4469695e09, global = 9.3509345e13, cumulative = 0.0021294309 GAMGPCG: Solving for p_rgh, Initial residual = 0.20976959, Final residual = 5.1609997e06, No Iterations 21 time step continuity errors : sum local = 1.2498129e12, global = 3.1235512e14, cumulative = 0.0021294309 ExecutionTime = 193.42 s ClockTime = 194 s Interface Courant Number mean: 1.2819201e10 max: 0.0018057993 Courant Number mean: 5.0481435e08 max: 0.29269287 deltaT = 9.8299463e16 Time = 0.0020815663602653 Selected 25 cells for refinement out of 97189. Refined from 97189 to 97364 cells. Selected 0 split points out of a possible 10256. Execution time for mesh.update() = 0.28 s time step continuity errors : sum local = 7.5998511e09, global = 3.7482614e14, cumulative = 0.0021294309 GAMGPCG: Solving for pcorr, Initial residual = 1, Final residual = 8.5199928e05, No Iterations 18 time step continuity errors : sum local = 6.4750677e13, global = 8.2134137e14, cumulative = 0.0021294309 MULES: Solving for alpha1 Phase1 volume fraction = 0.89999969 Min(alpha1) = 7.2610449e23 Max(alpha1) = 1.0000561 MULES: Solving for alpha1 Phase1 volume fraction = 0.89999969 Min(alpha1) = 1.3967872e22 Max(alpha1) = 1.0000561 MULES: Solving for alpha1 Phase1 volume fraction = 0.89999969 Min(alpha1) = 4.035089e22 Max(alpha1) = 1.0000561 GAMG: Solving for p_rgh, Initial residual = 0.17541847, Final residual = 0.0087247483, No Iterations 3 time step continuity errors : sum local = 6.4492676e09, global = 2.6064436e11, cumulative = 0.0021294309 GAMG: Solving for p_rgh, Initial residual = 0.16630811, Final residual = 0.0055667451, No Iterations 4 time step continuity errors : sum local = 4.3435881e09, global = 1.4441328e11, cumulative = 0.0021294309 GAMGPCG: Solving for p_rgh, Initial residual = 0.26960764, Final residual = 5.2469098e06, No Iterations 21 time step continuity errors : sum local = 3.252421e12, global = 5.7942249e14, cumulative = 0.0021294309 ExecutionTime = 194.51 s ClockTime = 195 s Christian Butcher Edit: The case is decomposed for 4 processors, in case that is relevant for the fact that some of the Courant numbers are in fact becoming higher, whilst others sit around 0.2. I assume this might be different processor regions. They are split using simple (2 2 1) and the mesh is cylindrical with the z axis as the axis of symmetry. The refinement is occurring at one end of the cylinder, for the higher z values (and should be at least approximately axisymmetric) Last edited by chrisb2244; August 26, 2013 at 01:17. Reason: Changed the region of output inserted as code. 

May 7, 2014, 04:49 

#2 
Senior Member
Artur
Join Date: May 2013
Location: Southampton, UK
Posts: 233
Rep Power: 6 
Hi Christian,
I am currently experiencing similar problems with interPhaseChangeFoam in 2.2.2. Have you found the solution to your problem and want to share? Peace, Artur 

May 8, 2014, 09:59 

#3 
Member
Christian Butcher
Join Date: Jul 2013
Location: Japan
Posts: 84
Rep Power: 4 
Dear Artur,
I'm afraid I don't remember now  I stopped working on that simulation at the end of August last year, and since then have been trying to set up and run other simulations/setups. Some of my current work is using interDyMFoam, or similar, and these do not suffer from the same problem (OF2.2.2, 2.3.0) so I can't really guess what might be the problem. Sorry for not having a useful response but thought this might be better than leaving you waiting here indefinitely. Good luck and best wishes, Christian 

July 1, 2014, 16:40 

#4 
Member
Gautami Erukulla
Join Date: Mar 2009
Posts: 40
Rep Power: 8 
Dear All,
I am using OpenFOAM version 2.2.0. I was able to run the tutorial "floating Object" which is in 3D in interDyMFoam without any issues. I am trying to run the same case in 2D. The following changes have been made, to run the case in 2D 1.In the blockMeshDict file the y coordinates range is changed. In 3D y axis range was from 0 to 1 and for 2D y axis range is changed as 0 to 0.1. For the front and back faces,created patch frontandback as empty 2.In the topoSetDict file: In 3D, box (0.35 0.35 0.44) (0.65 0.65 0.56) was changed in 2D as box (0.35 0.0 0.44) (0.65 0.1 0.56) 3.In the pointDisplacement file: In 3D floatingObject { type sixDoFRigidBodyDisplacement; centreOfMass (0.5 0.5 0.5); momentOfInertia (0.08622222 0.08622222 0.144); mass 9.6; rhoInf 1; // needed only for solvers solving for kinematic pressure report on; value uniform (0 0 0); } In 2D was changed as: floatingObject { type sixDoFRigidBodyDisplacement; centreOfMass (0.5 0.05 0.5); momentOfInertia (0.01952 0.08352 0.08); mass 9.6; rhoInf 1; // needed only for solvers solving for kinematic pressure report on; value uniform (0 0 0); } NOTE: Mass not changed With a change in mass,the changes are as follows: floatingObject { type sixDoFRigidBodyDisplacement; centreOfMass (0.5 0.05 0.5); momentOfInertia (0.08133 0.0348 0.033); mass 4.0; rhoInf 1; // needed only for solvers solving for kinematic pressure report on; value uniform (0 0 0); } 4.For all the boundary condition files in the folder 0,the patch frontandback is specified as empty. I run the case and and the run blows with delta T decreasing rapidly. > FOAM Warning : From function Time:perator++() in file db/Time/Time.C at line 1029 Increased the timePrecision from 12 to 13 to distinguish between timeNames at time 0.0444347581734 GAMG: Solving for p_rgh, Initial residual = 0.00606079623689, Final residual = 5.1801156616e05, No Iterations 2 time step continuity errors : sum local = 4.69383557933e05, global = 4.4792886392e07, cumulative = 0.000506180874993 GAMGPCG: Solving for p_rgh, Initial residual = 1.52101895333e05, Final residual = 6.35747944249e09, No Iterations 3 time step continuity errors : sum local = 0.000245342044169, global = 1.53144705592e06, cumulative = 0.000507712322048 smoothSolver: Solving for epsilon, Initial residual = 0.00132531232957, Final residual = 9.99802871216e07, No Iterations 41 bounding epsilon, min: 1.04792539095e+26 max: 8.15921076625e+28 average: 3.4517817453e+25 smoothSolver: Solving for k, Initial residual = 0.910004972962, Final residual = 0.0190942329344, No Iterations 1000 ExecutionTime = 120.48 s ClockTime = 121 s Interface Courant Number mean: 0.00473017730727 max: 14.3965768911 Courant Number mean: 2.42817054949 max: 10937.5681779 deltaT = 6.09445041823e18 Time = 0.04443475817338 Kindly can somebody please let me know where I am making a mistake and what I could do, to run the case in 2D successfully.Thank you. Regards, Gautami. 

Thread Tools  
Display Modes  


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
query regarding deltaT in multiphaseEulerFoam  bigboss.abhishek  OpenFOAM Running, Solving & CFD  6  September 24, 2015 15:56 
interDyMFoam deltaT drops nonstop  VirtualiCFD  OpenFOAM Running, Solving & CFD  5  June 12, 2015 04:30 
same geometry,structured and unstructured mesh,different behaviour.  sharonyue  OpenFOAM Running, Solving & CFD  13  January 2, 2013 23:40 
AMI speed performance  danny123  OpenFOAM  19  October 24, 2012 07:44 
How can deltaT exceed the limitation of courant?  yuhai  OpenFOAM Running, Solving & CFD  10  June 30, 2009 08:17 