[zhi]

Am trying to run a propeller simulation, exported propeller mesh from fluent. Faced this issue (below) after running the solver pimpleDyMFoam. Would appreciate any help given. Thank you!





PIMPLE: iteration 1
smoothSolver: Solving for Ux, Initial residual = 0.830223, Final residual = 0.0283056, No Iterations 2
smoothSolver: Solving for Uy, Initial residual = 0.829615, Final residual = 0.0415954, No Iterations 2
smoothSolver: Solving for Uz, Initial residual = 0.5632, Final residual = 0.0414705, No Iterations 1
GAMG: Solving for p, Initial residual = 0.999999, Final residual = 0.00540835, No Iterations 50
time step continuity errors : sum local = 1.92532e-09, global = 2.46904e-24, cumulative = 186.134
PIMPLE: iteration 2
smoothSolver: Solving for Ux, Initial residual = 0.733015, Final residual = 0.024106, No Iterations 1000
smoothSolver: Solving for Uy, Initial residual = 0.491305, Final residual = 0.052876, No Iterations 1000
smoothSolver: Solving for Uz, Initial residual = 0.329056, Final residual = 0.103363, No Iterations 1000
GAMG: Solving for p, Initial residual = 1.29579e-74, Final residual = 1.29579e-74, No Iterations 0
time step continuity errors : sum local = 3.30903e-05, global = -2.40714e-20, cumulative = 186.134
smoothSolver: Solving for epsilon, Initial residual = 0.0333985, Final residual = 1.28648e-29, No Iterations 1
bounding epsilon, min: -3.03335e+73 max: 2.81081e+115 average: 1.12218e+112
smoothSolver: Solving for k, Initial residual = 0.975129, Final residual = 3.93831e-07, No Iterations 10
bounding k, min: -1.11196e+72 max: 2.25176e+89 average: 5.29295e+85
ExecutionTime = 79.94 s ClockTime = 80 s

forces forces write:
sum of forces:
pressure : (-1.44919e+163 -2.63952e+163 -5.38618e+163)
viscous : (-4.04839e+80 -8.72261e+80 1.35115e+81)
porous : (0 0 0)
sum of moments:
pressure : (-8.62455e+163 -1.67949e+164 1.05508e+164)
viscous : (-3.71479e+81 -1.21225e+82 2.94079e+81)
porous : (0 0 0)

Courant Number mean: 4.20985e-05 max: 228.707
deltaT = 4.33277e-47
Time = 8.98156e-06

PIMPLE: iteration 1
smoothSolver: Solving for Ux, Initial residual = 0.994349, Final residual = 0.0301236, No Iterations 2
smoothSolver: Solving for Uy, Initial residual = 0.999124, Final residual = 0.0303918, No Iterations 2
smoothSolver: Solving for Uz, Initial residual = 0.905924, Final residual = 0.0273474, No Iterations 2
GAMG: Solving for p, Initial residual = 0.859546, Final residual = nan, No Iterations 50
time step continuity errors : sum local = nan, global = -nan, cumulative = -nan
PIMPLE: iteration 2
smoothSolver: Solving for Ux, Initial residual = nan, Final residual = nan, No Iterations 1000
smoothSolver: Solving for Uy, Initial residual = nan, Final residual = nan, No Iterations 1000
smoothSolver: Solving for Uz, Initial residual = nan, Final residual = nan, No Iterations 1000
GAMG: Solving for p, Initial residual = nan, Final residual = nan, No Iterations 50


--> FOAM FATAL IO ERROR:
wrong token type - expected Scalar, found on line 0 the word 'nan'

file: /scratch/users/nus/e0004344/ansyslowmesh/test1/system/data.solverPerformance.p at line 0.

From function Foam::Istream& Foam:perator>>(Foam::Istream&, Foam::doubleScalar&)
in file lnInclude/Scalar.C at line 93.

FOAM exiting

[clapointe]

Check out the log file -- there are large continuity errors and your velocity equations do not even converge for the first iteration. This suggests a flaw in case set up. I've not used pimpleDyMFoam before, but I know that its functionality was recently merged with pimpleFoam. Check out this tutorial -- it is also a propeller simulation : https://github.com/OpenFOAM/OpenFOAM.../RAS/propeller.

Caelan

[zhi]

Hi Caelan,

Thank you for your prompt reply.

I have tried running the propeller tutorial that you tagged. In my current propeller simulation, i based off the initial boundary conditions from the propeller tutorial.

What do you mean by the errors and the velocity equations do not converge for the first iteration? Do you have an example when it does converge? Sorry, i am very new to openfoam.

Thank you!

[clapointe]

In the log output you posted -- the Ux/y/z solvers reach 1000 iterations (this is the default maximum), the continuity error is very very large, and your k/epsilon bounds are off the charts. I can't offer any expertise with the solver, but as I said these errors indicate a problem with the case setup. If your mesh is alright (run checkMesh and see if any errors pop up), then it's probably a boundary condition issue.

Caelan

[zhi]

Hi Caelan,

I ran checkMesh and there wasnt any issue with my mesh.

Do you have any idea how to solve the issue with the boundary condition?

Below is the log file for my checkMesh.
Create time

Create polyMesh for time = 0

Time = 0

Mesh stats
points: 18107
internal points: 15049
faces: 201198
internal faces: 195098
cells: 99074
faces per cell: 4
boundary patches: 5
point zones: 0
face zones: 2
cell zones: 2

Overall number of cells of each type:
hexahedra: 0
prisms: 0
wedges: 0
pyramids: 0
tet wedges: 0
tetrahedra: 99074
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: 2
The mesh has multiple regions which are not connected by any face.
<<Writing region information to "0/cellToRegion"
<<Writing region 0 with 77075 cells to cellSet region0
<<Writing region 1 with 21999 cells to cellSet region1

Checking patch topology for multiply connected surfaces...
Patch Faces Points Surface topology
inlet 158 95 ok (non-closed singly connected)
outlet 136 84 ok (non-closed singly connected)
surrounding 1086 573 ok (non-closed singly connected)
propeller 2682 1343 ok (closed singly connected)
default_wall 2038 1023 ok (closed singly connected)

Checking geometry...
Overall domain bounding box (-58.5 -58.4997 -58.5) (58.5 58.5 117)
Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
Mesh has 3 solution (non-empty) directions (1 1 1)
Boundary openness (1.27662e-17 -1.38572e-17 -8.24011e-18) OK.
Max cell openness = 2.55068e-16 OK.
Max aspect ratio = 5.9895 OK.
Minimum face area = 0.00187105. Maximum face area = 174.394. Face area magnitudes OK.
Min volume = 5.00739e-05. Max volume = 860.135. Total volume = 1.87714e+06. Cell volumes OK.
Mesh non-orthogonality Max: 63.4043 average: 16.2521
Non-orthogonality check OK.
Face pyramids OK.
Max skewness = 0.846399 OK.
Coupled point location match (average 0) OK.

Mesh OK.

End

[clapointe]

It is hard to diagnose problems without seeing the case. A first step would be to try running without mesh/propellor motion. This will separate the DyM functionality from the solver -- might help to isolate your problem.

Caelan

[richengle]

i got same problem, and had to decrease my sim step time by a factor of 1/100... like from 5e-3 to 5e-5