How to set up inviscid flow over a cylinder

[jieb]

How to set up inviscid flow over a cylinder? Can I just set viscosity =0.0? and set the normal direction velocity =0.0 and leave the tangential direction velocity free?
Here is my *.sif file

Code: Select all

Header
  CHECK KEYWORDS Warn
  Mesh DB "." "."
  Include Path ""
  Results Directory ""
End

Simulation
  Max Output Level = 4
  Coordinate System = Cartesian 2D
!  Coordinate Mapping(3) = 1 2 3
  Simulation Type = Steady State
  Steady State Min Iterations = 1
  Steady State Max Iterations = 1
!  Output Intervals = 1
!  Timestepping Method = BDF
!  BDF Order = 2
!  Timestep intervals = 200
!  Timestep Sizes = $ 8.0/200
  Solver Input File = case.sif
!  Post File = case.ep
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

Solver 1
  Equation = Navier-Stokes
  Procedure = "FlowSolve" "FlowSolver"
  Variable = Flow Solution[Velocity:2 Pressure:1]
  Exec Solver = Always
  Stabilize = True
  Bubbles = False
  Lumped Mass Matrix = False
  Optimize Bandwidth = True
  Steady State Convergence Tolerance = 1.0e-5
  Nonlinear System Convergence Tolerance = 1.0e-4
  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-6
  Linear System Preconditioning = ILU0
  Linear System ILUT Tolerance = 1.0e-3
  Linear System Abort Not Converged = False
  Linear System Residual Output = 1
  Linear System Precondition Recompute = 1
End

Solver 2
  Exec Solver = after all
  Equation = "ResultOutput"
  Procedure = "ResultOutputSolve" "ResultOutputSolver"
  Output File Name = result
  Vtu Format = Logical True
  Scalar Field 1 = "Pressure"
  Vector Field 1 = "Velocity"
End

Equation 1
  Name = "Navier-Stokes"
  Active Solvers(2) = 1 2
End

Material 1
  Name = "Ideal"
  Viscosity = 0.0
  Density = 1
End

Boundary Condition 1
  Target Boundaries(1) = 4
  Name = "Inlet"
  Velocity 1 = 1.0
  Velocity 2 = 0.0
End

Boundary Condition 2
  Target Boundaries(1) = 2
  Name = "Outlet"
  Velocity 2 = 0.0
End

Boundary Condition 3
  Target Boundaries(1) = 1
  Name = "Walls"
  Velocity 2 = 0.0
End

Boundary Condition 4
  Target Boundaries(1) = 5
  Name = "CircWall"
  Normal-Tangential Velocity = Logical True
  Velocity 1 = Real 0.0e0
End

The test does NOT converge.

[raback]

Hi

When viscosity in N-S equations goes to zero Re number goes to infinity and the solver cannot deal with that. The resulting set of equations is known as Euler's equations. So you need a numerical solution for that equation. If you find references it would be interesting to know how that is optimally solved with the Finite Element method.

-Peter

[jieb]

Hi Peter,

Thanks for the response.
Is there any way to simulate inviscid flow in Elmer? if there is no Euler equation solver in Elmer.

Thanks

Jie