3D free surface problem

N. Takashi · Post by **N. Takashi** » 17 Jun 2010, 07:30

Hi, Elmer team and all users.

I am new user of Elmer and have some problems.
If you know how to solve them, please let me know.

My problem is 3D Poiseuille flow with free surface.
I want to simulate the flow aspects when water flowing in the rectangle,
Boundary conditions are inlet, outlet, sides, free surface and bottom,
and I find out the following erro messages;

Code: Select all

ComputeChange: SS (ITER=1) (NRM,RELC): ( 0.18196624E-02  2.0000000     ) :: navier-stokes
FreeSurfaceSolver (freesurface): Velocity implicity (1=fully implicit)=    1.00
FreeSurfaceSolver (freesurface): Using residual squared-stabilized formulation.
FreeSurfaceSolver (freesurface): DIM=3
FreeSurfaceSolver (freesurface): Memory allocations done
FreeSurfaceSolver (freesurface): Non-linear Iteration    1 out of max.    1
FreeSurfaceSolver (freesurface): start assembly
ERROR:: ElementMetric:  Degenerate 2D element:  -7.30548307107074613E-026
ERROR:: ElementMetric:  Degenerate 2D element:  -7.30548307107074613E-026
ERROR:: ElementMetric:  Degenerate 2D element:  -7.30548307107074613E-026
ERROR:: ElementMetric:  Degenerate 2D element:  -8.36571212768778599E-026
ERROR:: ElementMetric:  Degenerate 2D element:  -8.36571212768778599E-026
ERROR:: ElementMetric:  Degenerate 2D element:  -8.36571212768778599E-026
ERROR:: ElementMetric:  Degenerate 2D element:  -5.10602048516732923E-020
ERROR:: ElementMetric:  Degenerate 2D element:  -5.10602048516732923E-020
ERROR:: ElementMetric:  Degenerate 2D element:  -5.10602048516732923E-020
.............................................................................................. 
.............................................................................................. 
.............................................................................................. 
..............................................................................................

Sif is...

Code: Select all

Body 1
Target Bodies(1) = 1
Name = "Body 1"
Equation = 1
Material = 1
Initial condition = 1
Body Force=1
End

Body 2
Target Bodies(1) = 2
Name = "Body 2"
Equation = 2
Material = 1
Initial condition = 1
Body Force=1
End

Solver 1
...................
End

Solver 2
...................
End

Solver 3
...................
End

Equation 1
Name = "Equation 1"
NS Convect = "computed"
Active Solvers(2) = 1 3
End

Equation 2
Active Solvers(1) = 2
Convection = "computed"
Flow Solution Name = String "Flow Solution"
End

Material 1
Density = 998.3
Viscosity = 1.002e-3
Youngs Modulus = 1000000.0
Poisson Ratio = 0.49999
End

Initial Condition 1
Name = "InitialCondition 1"
Velocity 3 = 0
Velocity 2 = 0
Velocity 1 = 0.01
Pressure = 0
Mesh Update 1 = 0
Mesh Update 2 = 0
Mesh Update 3 = 0
End

Boundary Condition 1
Target Boundaries(1) = 1
Name = "Outlet"
Velocity 2 = 0
Velocity 3 = 0
Velocity 1 = 0.01

Mesh Update 1 = Real 0.0
Mesh Update 2 = Real 0.0
Mesh Update 3 = Real 0.0
End

Boundary Condition 2
Target Boundaries(1) = 2
Name = "Wall"
Noslip wall BC = True

Mesh Update 1 = 0
Mesh Update 2 = 0
Mesh Update 3 = 0
End

Boundary Condition 3
Target Boundaries(1) = 3
Name = "Bottom"
Noslip wall BC = True

Mesh Update 1 = 0
Mesh Update 2 = 0
Mesh Update 3 = 0
End

Boundary Condition 4
Target Boundaries(1) = 5
Name = "Free"

Body id = 2
Flow Force BC = True
Surface Tension Coefficient = 0.0 

Mesh Update 2 = Equals FreeSurface
End

Boundary Condition 5
Target Boundaries(1) = 6
Name = "Inlet"
Velocity 1 = 0.01
Velocity 2 = 0
Velocity 3 = 0

Mesh Update 1 = 0
Mesh Update 2 = 0
Mesh Update 3 = 0
End

I really strand and want to solve this problem!
I would appriciate if you would help me out.

Regards
Takashi