I'm trying to learn how to do a coupled fluid flow and heat simulation.
I have a simple geometry with a cube (air) and a hot plate:
Steady state does converge after I set in solver Navier-Stokes:
Nonlinear System Newton After Iterations = 100
Nonlinear System Newton After Tolerance = 0.0
However, in Transient mode, it fails after on the second timestep:
Code: Select all
MAIN: -------------------------------------
MAIN: Time: 2/10 20.000000000000000
MAIN: Estimated time left: 4.3 hours
MAIN: -------------------------------------
MAIN:
...
FlowSolve: -------------------------------------
FlowSolve: NAVIER-STOKES ITERATION 1
FlowSolve: -------------------------------------
FlowSolve:
...
490 0.3719E-03
500 0.7719E-01
501 0.7719E-01
ERROR:: IterSolve: Numerical Error: Too many iterations were needed.
Note: The following floating-point exceptions are signalling: IEEE_UNDERFLOW_FLAG IEEE_DENORMAL
STOP 1
Code: Select all
Header
CHECK KEYWORDS Warn
Mesh DB "." "."
Include Path ""
Results Directory ""
End
Simulation
Max Output Level = 5
Coordinate System = Cartesian
Coordinate Mapping(3) = 1 2 3
Simulation Type = Transient
Steady State Max Iterations = 1
Output Intervals = 1
Timestepping Method = BDF
BDF Order = 1
Timestep intervals = 10
Timestep Sizes = 10
Coordinate Scaling = 0.001
Solver Input File = case.sif
Post File = case.vtu
End
Constants
Gravity(4) = 0 -1 0 9.82
Stefan Boltzmann = 5.67e-08
Permittivity of Vacuum = 8.8542e-12
Boltzmann Constant = 1.3807e-23
Unit Charge = 1.602e-19
End
Body 1
Target Bodies(1) = 3
Name = "Body 1"
Equation = 1
Material = 1
Body Force = 1
Initial condition = 1
End
Solver 1
Equation = Result Output
Single Precision = True
Output Format = Vtu
Output File Name = case
Procedure = "ResultOutputSolve" "ResultOutputSolver"
Exec Solver = Always
End
Solver 3
Equation = Heat Equation
Procedure = "HeatSolve" "HeatSolver"
Variable = Temperature
Exec Solver = After Timestep
Stabilize = True
Bubbles = False
Lumped Mass Matrix = False
Optimize Bandwidth = True
Steady State Convergence Tolerance = 1.0e-5
Nonlinear System Convergence Tolerance = 1.0e-7
Nonlinear System Max Iterations = 20
Nonlinear System Newton After Iterations = 3
Nonlinear System Newton After Tolerance = 1.0e-3
Nonlinear System Relaxation Factor = 1
Linear System Solver = Iterative
Linear System Iterative Method = BiCGStab
Linear System Max Iterations = 500
Linear System Convergence Tolerance = 1.0e-10
BiCGstabl polynomial degree = 2
Linear System Preconditioning = ILU0
Linear System ILUT Tolerance = 1.0e-3
Linear System Abort Not Converged = True
Linear System Residual Output = 10
Linear System Precondition Recompute = 1
End
Solver 2
Equation = Navier-Stokes
Variable = Flow Solution[Velocity:3 Pressure:1]
Procedure = "FlowSolve" "FlowSolver"
Exec Solver = After Timestep
Stabilize = False
Bubbles = True
Lumped Mass Matrix = False
Optimize Bandwidth = True
Steady State Convergence Tolerance = 1.0e-5
Nonlinear System Convergence Tolerance = 1.0e-7
Nonlinear System Max Iterations = 20
Nonlinear System Newton After Iterations = 100
Nonlinear System Newton After Tolerance = 0.0
Nonlinear System Relaxation Factor = 1
Linear System Solver = Iterative
Linear System Iterative Method = BiCGStab
Linear System Max Iterations = 500
Linear System Convergence Tolerance = 1.0e-7
BiCGstabl polynomial degree = 2
Linear System Preconditioning = ILU0
Linear System ILUT Tolerance = 1.0e-3
Linear System Abort Not Converged = True
Linear System Residual Output = 10
Linear System Precondition Recompute = 1
End
Equation 1
Name = "Equation 1"
Convection = Computed
Active Solvers(3) = 1 3 2
End
Material 1
Name = "Air (room temperature)"
Heat expansion Coefficient = 3.43e-3
Relative Permittivity = 1.00059
Heat Conductivity = 0.0257
Heat Capacity = 1005.0
Viscosity = 1.983e-5
Reference Temperature = 293
Sound speed = 343.0
Density = 1.205
End
Body Force 1
Name = "BodyForce 1"
Boussinesq = True
End
Initial Condition 1
Name = "InitialCondition 1"
Velocity 1 = 0
Temperature = 293
Velocity 2 = 1e-9
End
Boundary Condition 1
Target Boundaries(1) = 2
Name = "Wall"
Noslip wall BC = True
Temperature = 293
End
Boundary Condition 2
Target Boundaries(1) = 1
Name = "Plate"
Noslip wall BC = True
Temperature = 300
End
https://www.dropbox.com/s/9hvv0l9th9dzo ... e.zip?dl=0
I did try to set ILU(3) for Navier-Stokes but it craches ElmerSolver
Code: Select all
: ....Assembly done
DefUtils::DefaultDirichletBCs: Setting Dirichlet boundary conditions
DefUtils::DefaultDirichletBCs: Dirichlet boundary conditions set
FlowSolve: Dirichlet conditions done
CRS_IncompleteLU: ILU(3) (Real), Starting Factorization:
Program received signal SIGFPE: Floating-point exception - erroneous arithmetic operation.
Backtrace for this error:
#0 0x7f32ffd902ed in ???
#1 0x7f32ffd8f503 in ???
#2 0x7f32ff9c2f1f in ???
#3 0x7f3300271d99 in __generalutils_MOD_i2s
at /build/elmerfem-csc-eg-mNdSQS/elmerfem-csc-eg-8.4-0ppa0/fem/src/GeneralUtils.F90:199
#4 0x7f330028f333 in initializeilu1
at /build/elmerfem-csc-eg-mNdSQS/elmerfem-csc-eg-8.4-0ppa0/fem/src/CRSMatrix.F90:3333
#5 0x7f3300298fa0 in __crsmatrix_MOD_crs_incompletelu
at /build/elmerfem-csc-eg-mNdSQS/elmerfem-csc-eg-8.4-0ppa0/fem/src/CRSMatrix.F90:3083
#6 0x7f33002cdfe6 in __itersolve_MOD_itersolver
at /build/elmerfem-csc-eg-mNdSQS/elmerfem-csc-eg-8.4-0ppa0/fem/src/IterSolve.F90:712
#7 0x7f3300381799 in __solverutils_MOD_solvelinearsystem
at /build/elmerfem-csc-eg-mNdSQS/elmerfem-csc-eg-8.4-0ppa0/fem/src/SolverUtils.F90:12857
#8 0x7f330037c319 in __solverutils_MOD_solvesystem
at /build/elmerfem-csc-eg-mNdSQS/elmerfem-csc-eg-8.4-0ppa0/fem/src/SolverUtils.F90:13236
#9 0x7f33004ca00e in __defutils_MOD_defaultsolve
at /build/elmerfem-csc-eg-mNdSQS/elmerfem-csc-eg-8.4-0ppa0/fem/src/DefUtils.F90:3263
#10 0x7f32dfbc3d61 in flowsolver_
at /build/elmerfem-csc-eg-mNdSQS/elmerfem-csc-eg-8.4-0ppa0/fem/src/modules/FlowSolve.F90:1261
#11 0x7f330038b8fb in __mainutils_MOD_singlesolver
at /build/elmerfem-csc-eg-mNdSQS/elmerfem-csc-eg-8.4-0ppa0/fem/src/MainUtils.F90:5161
#12 0x7f330039f1a8 in __mainutils_MOD_solveractivate
at /build/elmerfem-csc-eg-mNdSQS/elmerfem-csc-eg-8.4-0ppa0/fem/src/MainUtils.F90:5403
#13 0x7f33003a19df in __mainutils_MOD_solveequations
at /build/elmerfem-csc-eg-mNdSQS/elmerfem-csc-eg-8.4-0ppa0/fem/src/MainUtils.F90:2962
#14 0x7f330059c189 in execsimulation
at /build/elmerfem-csc-eg-mNdSQS/elmerfem-csc-eg-8.4-0ppa0/fem/src/ElmerSolver.F90:2441
#15 0x7f330059c189 in elmersolver_
at /build/elmerfem-csc-eg-mNdSQS/elmerfem-csc-eg-8.4-0ppa0/fem/src/ElmerSolver.F90:477
#16 0x5586d9a5117b in solver
at /build/elmerfem-csc-eg-mNdSQS/elmerfem-csc-eg-8.4-0ppa0/fem/src/Solver.F90:69
#17 0x5586d9a50ece in main
at /build/elmerfem-csc-eg-mNdSQS/elmerfem-csc-eg-8.4-0ppa0/fem/src/Solver.F90:34
Franck.