If the initial guess of the heat source is 500 W/kg with a setpoint temperature of the smart heater of 923 K I get the following results:
Time (s)--------------------Power Density (W/kg)
3.600000000000E+003 9.551616693502E+002
7.200000000000E+003 5.279649006690E+002
1.080000000000E+004 4.409886676690E+002
1.440000000000E+004 3.996450815166E+002
1.800000000000E+004 3.776308097251E+002
2.160000000000E+004 3.641013732455E+002
2.520000000000E+004 3.547031022428E+002
However, if the initial guess of the heat source is 90 W/kg with a setpoint temperature of the smart heater of 923 K, I get these results:
Time (s)---------------------Power Density (W/kg)
3.600000000000E+003 5.492029620666E+002
7.200000000000E+003 1.953290766480E+002
1.080000000000E+004 1.631571755695E+002
1.440000000000E+004 1.478636815313E+002
1.800000000000E+004 1.397188460322E+002
2.160000000000E+004 1.347129985598E+002
2.520000000000E+004 1.312368548457E+002
Edit: I should note that the heater temperature in both cases is the same when I check it in post.
Here's my sif file:
Code: Select all
Header
CHECK KEYWORDS Warn
Mesh DB "." "."
Include Path ""
Results Directory ""
End
Simulation
Max Output Level = 5
Coordinate System = "Cartesian 2D"
Coordinate Mapping(3) = 1 2 3
Simulation Type = Transient
Steady State Max Iterations = 30
Timestepping Method = BDF
BDF Order = 1
! Timestep Intervals(3) = 1 48 179
! Timestep Sizes(3) = 0.001 1800 86400
Timestep Intervals(1) = 180
Timestep Sizes(1) = 3600
! Output Intervals(3) = 1 24 1
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
!---------------------------------------------------------------------
Initial Condition 1
Name = "InitialCondition 1"
Temperature = 293.15
End
!---------------------------------------------------------------------
Body Force 1
Name = "Heater"
Heat Source = 93.86
Smart Heater Control = Logical True
Smart Heater Temperature = Real MATC "273.15 + 650"
Smart Heater Control Point(3) = 0.0281585 0.00813963 0.0
End
!---------------------------------------------------------------------
Material 1
Name = "Soil"
Heat Conductivity = Variable Temperature
Real
Include TC.dat
End
Heat Capacity = 800
Density = 2200
End
Material 2
Name = "Steel"
Sound speed = 5100.0
Youngs modulus = 200.0e9
Poisson ratio = 0.285
Mesh Poisson ratio = 0.285
Heat expansion Coefficient = 13.8e-6
Heat Conductivity = 44.8
Density = 7850.0
Heat Capacity = 1265.0
End
Material 3
Name = "Air"
Heat Capacity = Variable Temperature
Real
Include CP-Air.dat
End
Heat Conductivity = Variable Temperature
Real
Include TC-Air.dat
End
Density = Variable Temperature
Real
Include D-Air.dat
End
End
!---------------------------------------------------------------------
Body 1
Name = "Core"
Equation = 1
Material = 2
Initial condition = 1
Body Force = 1
End
Body 2
Name = "Casing"
Equation = 1
Material = 2
Initial condition = 1
End
Body 3
Name = "Soil"
Equation = 1
Material = 1
Initial condition = 1
End
Body 4
Name = "AirInner"
Equation = 1
Material = 3
Initial condition = 1
End
Body 5
Name = "AirOuter"
Equation = 1
Material = 3
Initial condition = 1
End
!---------------------------------------------------------------------
Boundary Condition 1
Name = "Heater"
Target Boundaries(1) = 1
Save Scalars = True
Radiation Boundary = 1
Radiation = Diffuse Gray
Emissivity = 0.80
End
Boundary Condition 2
Name = "InnerCasing"
Target Boundaries(1) = 4
Radiation Boundary = 1
Radiation = Diffuse Gray
Emissivity = 0.80
End
!---------------------------------------------------------------------
Equation 1
Name = "Equation 1"
Active Solvers(3) = 1 2 3
End
!---------------------------------------------------------------------
Solver 1
Equation = Heat Equation
Procedure = "HeatSolve" "HeatSolver"
Variable = Temperature
Exec Solver = Always
Stabilize = True
Bubbles = False
Lumped Mass Matrix = False
Optimize Bandwidth = True
Calculate Loads = True
Calculate Boundary Weights = True
Calculate Flux = 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 = Diagonal
Linear System ILUT Tolerance = 1.0e-3
Linear System Abort Not Converged = False
Linear System Residual Output = 1
Linear System Precondition Recompute = 1
! Update View Factors = True
! Update Gebhardt Factors = True
End
Solver 2
Exec Solver = Before Saving
Equation = SaveScalars
Procedure = "SaveData" "SaveScalars"
Filename = save scalars.dat
Variable 1 = Time
! Variable 2 = Temperature
! Operator 2 = max
! Target Variable 2 = String maxTemp
! Variable 3 = Heat Source
End
Solver 3
Equation = Result Output
Procedure = "ResultOutputSolve" "ResultOutputSolver"
Output Format = Vtu
vtu time collection = logical true
Output File Name = case
Exec Solver = Before Saving
End