Question

[dalfa...@ut.ac.ir]

Hi
Sorry to write and ask so much here.
I want to do spin up but every change in time parameters lead to failure in time steps. I changed solver settings and also some time parameters like growth factor and initial step and tried different range, large and small time step and also solver setting like nni, but it shows again failure in kinsol log file and in log file showed this sentence:Node 0: Error: Time step failed for time ....., what is the reason or resons?
What are the most important factors that should take into considerate to adress this problem?
this are my solver settings:
pfset Solver Richards
pfset Solver.MaxIter 40000
#pfset OverlandFlowDiffusive 0
pfset Solver.TerrainFollowingGrid True
#pfset Solver.Nonlinear.VariableDz True
pfset Solver.Nonlinear.MaxIter 500
pfset Solver.Nonlinear.ResidualTol 1e-6
pfset Solver.Nonlinear.EtaChoice EtaConstant
pfset Solver.Nonlinear.EtaValue 0.01
pfset Solver.Nonlinear.UseJacobian True
pfset Solver.Nonlinear.DerivativeEpsilon 1e-16
pfset Solver.Nonlinear.StepTol 1e-20
pfset Solver.Nonlinear.Globalization LineSearch
pfset Solver.Linear.KrylovDimension 55
pfset Solver.Linear.MaxRestart 8
pfset Solver.MaxConvergenceFailures 5

pfset Solver.Linear.Preconditioner PFMG
pfset Solver.Linear.Preconditioner.PCMatrixType FullJacobian
#pfset Solver.Linear.Preconditioner MGSemi
#pfset Solver.Linear.Preconditioner.MGSemi.MaxIter 1
#pfset Solver.Linear.Preconditioner.MGSemi.MaxLevels 10
pfset Solver.Drop 1E-20
pfset Solver.AbsTol 1E-9

pfset Solver.PrintSaturation True
pfset Solver.PrintSubsurf True
pfset Solver.PrintPressure True
pfset Solver.PrintMask True
The followings are my time parameters:
pfset TimingInfo.BaseUnit 1.0
pfset TimingInfo.StartCount 0
pfset TimingInfo.StartTime 0.0
pfset TimingInfo.StopTime 10000000.0
pfset TimingInfo.DumpInterval 720.0
pfset TimeStep.Type Growth
pfset TimeStep.InitialStep 1
pfset TimeStep.GrowthFactor 1.1
pfset TimeStep.MaxStep 10000000.0
pfset TimeStep.MinStep 1.0
#pfset TimeStep.Value 1.0
this is a log out sample file:
Node 0: Using process grid (2,1,1)
Node 0: Well Information
Node 0: No Wells.
Node 0: Error: Time step failed for time 1.1000e+01.
Node 0: Shutting down.
Node 0: Well Information
Node 0: No Wells.
Node 0: Problem solved
The followings are a sample of first time step in kinsol log file:
KINSOL starting step for time 1.100000
scsteptol used: 1e-20
fnormtol used: 1e-06
KINSolInit nni= 0 fnorm= 3564784.152196603 nfe= 1
KINSol nni= 1 fnorm= 1689851.556685722 nfe= 2
KINSol nni= 2 fnorm= 801189.0102327373 nfe= 3
KINSol nni= 3 fnorm= 379918.5232248941 nfe= 4
KINSol nni= 4 fnorm= 180182.6572637543 nfe= 5
KINSol nni= 5 fnorm= 85467.40880496865 nfe= 6
KINSol nni= 6 fnorm= 40546.29163085994 nfe= 7
KINSol nni= 7 fnorm= 19238.12951254541 nfe= 8
KINSol nni= 8 fnorm= 9129.221182038469 nfe= 9
KINSol nni= 9 fnorm= 4332.732788293959 nfe= 10
KINSol nni= 10 fnorm= 2056.579571140679 nfe= 11
KINSol nni= 11 fnorm= 976.2987730966752 nfe= 12
KINSol nni= 12 fnorm= 463.0741879848337 nfe= 13
KINSol return value 8
---KINSOL_KRYLOV_FAILURE

--------------------------------------------------
Iteration Total
Nonlin. Its.: 13 13
Lin. Its.: 67 67
Func. Evals.: 13 13
PC Evals.: 13 13
PC Solves: 79 79
Lin. Conv. Fails: 1 1
Beta Cond. Fails: 0 0
Backtracks: 0 0
I tried testing a lot of alternation in this parameters but all didn't work, Is there any guide or help please?
Sadegh