SaveScalars in parallel

[RubenNavas]

Hello,
I'm performing a simulation of the flow passed an airfoil by using ElmerGUI. One of the objectives is to calculate the lift and drag forces. To do so, I'm using the "Calculate Loads" in the Navier-Stokes solver and summing them over the airfoil using the SaveScalars solver. The .sif code parts are hereafter detailed:

The Navier-Stokes part:

Code: Select all

Solver 2
  Equation = Navier-Stokes
  Calculate Loads = True
  Procedure = "FlowSolve" "FlowSolver"
  Variable = Flow Solution[Velocity:2 Pressure:1]
  Exec Solver = Always
  Stabilize = True
  Optimize Bandwidth = True
  Steady State Convergence Tolerance = 1.0e-5
  Nonlinear System Convergence Tolerance = 1.0e-4
  Nonlinear System Max Iterations = 10
  Nonlinear System Newton After Iterations = 3
  Nonlinear System Newton After Tolerance = 1.0e-3
  Nonlinear System Relaxation Factor = 0.5
  Linear System Solver = Iterative
  Linear System Iterative Method = BiCGStab
  Linear System Max Iterations = 1000000
  Linear System Convergence Tolerance = 1.0e-6
  BiCGstabl polynomial degree = 2
  Linear System Preconditioning = ILU0
  Linear System ILUT Tolerance = 1.0e-3
  Linear System Abort Not Converged = False
  Linear System Residual Output = 10
  Linear System Precondition Recompute = 1
End

The SaveScalars solver:

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Solver 1
  Equation = SaveScalars
  Procedure = "SaveData" "SaveScalars"
  Variable 1 = Flow Solution Loads 1
  Parallel Reduce = True
  Operator 1 = boundary sum
  File Append = True
  Variable 2 = Flow Solution Loads 2
  Filename = fluidForces.dat
  Exec Solver = Always
End

The airfoil boundary condition:

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Boundary Condition 3
  Target Boundaries(1) = 8 
  Name = "Airfoil"
  Noslip wall BC = True
  Save Scalars = True
End

Nevertheless, when I execute the simulation in parallel I get a strange error, which does not appear if the simulation is ran in sequential. Additionally, I submit the entire .sif and the error output.

Thanks for the help.