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Old   July 26, 2011, 11:32
Default Time step continuity errors
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Unnikrishnan
Join Date: Jun 2011
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Dear Foamer,

I have the following doubt.

In Fueltank Simulation with Gasoline and Air. using InterFoam Solver..
I have the problem with the Simulation taking a long time to run.



Case 1:
MULES: Solving for alpha1
Liquid phase volume fraction = 0.26 Min(alpha1) = -8.2e-45 Max(alpha1) = 1
MULES: Solving for alpha1
Liquid phase volume fraction = 0.26 Min(alpha1) = -6.1e-44 Max(alpha1) = 1
FDICPCG: Solving for p, Initial residual = 9.5e-05, Final residual = 9.8e-08, No Iterations 135
FDICPCG: Solving for p, Initial residual = 4.5e-05, Final residual = 9.5e-08, No Iterations 131
time step continuity errors : sum local = 3.4e-09, global = 9.7e-12, cumulative = -0.55
ExecutionTime = 2.1e+03 s ClockTime = 2128 s

Courant Number mean: 0.013 max: 0.5
deltaT = 8.4e-05
Time = 0.0037

Case 2:
MULES: Solving for alpha1
Liquid phase volume fraction = 0.284091 Min(alpha1) = 0 Max(alpha1) = 1
MULES: Solving for alpha1
Liquid phase volume fraction = 0.284122 Min(alpha1) = 0 Max(alpha1) = 1
DICPCG: Solving for p, Initial residual = 0.00298799, Final residual = 0.000131926, No Iterations 9
DICPCG: Solving for p, Initial residual = 0.000792862, Final residual = 3.83134e-05, No Iterations 24
DICPCG: Solving for p, Initial residual = 0.000115893, Final residual = 7.5165e-08, No Iterations 190
time step continuity errors : sum local = 1.06601e-08, global = 3.61895e-10, cumulative = -1.09828e-08
ExecutionTime = 51.02 s ClockTime = 51 s


With Case 1
0 -> 0.0021 ( 1392 s )
0 -> 10 ( 1841.2 hrs )


I want to reduce the total Time for Simulation.
I had tried changing the ControlDict But there is no change
deltaT 0.1; -> 0.01 ->0.001
writeControl adjustableRunTime;
writeInterval 0.005; -> 0.0005 ->0.00005
(for 0.00005 i am able to find some Writefiles and Some results in openfoam )


Trials done :
I had tried Changing the Pressure values,
I had tried Changing the Velocity Values,
Maintaining different Values at both Ends.
But there is no change in simulation timings.


Changing Fvsolution
Pcorr
DIC -> FDIC
reltol 0 -> 1e-05
P
DIC -> FDIC
reltol 0 -> 1e-03
pfinal
DIC -> FDIC
reltol 0 -> 1e-03
U
reltol 0 -> 1e-03

Piso
ncorrector 3 -> 2


But still there is not change in the following problem..
I would first like the check if the simulation is running..

I could latter check about the results..



Regards
Unnikrishnan
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