Hi, I'm new in this forum and new user of elmer. PLease tell me what is wrong with my simulation. I analized flow from this article
"https://www.google.pl/url?sa=t&rct=j&q= ... Gg&cad=rja"
It's about fluid velocity development in laminar pipe flow. The inner diameter is 24mm, medium is water in room temp. Profile of full development velocity should be after 1,33m. Vo=38,7mm/s and expected Vmax after 1,33m flow is 77,4mm/s.
In my Elmer's simulation Vmax=58mm/s
In laminar flow in pipe Vmax=2xVo. In Elmers simulation Vmax=1,5xVo , What is wrong?
I attach my results
Please answer
Wojtek
Laminar flow in pipewrong results
Laminar flow in pipewrong results
 Attachments

 Molki Elmer.jpg
 Elmers results by Paraview
 (79.27 KiB) Not downloaded yet
Re: Laminar flow in pipewrong results
Now i know what's wrong. I used rectangular mesh and coordinate system as cartesian so the case is as caonical flow (like in tutorial 6) How to set boundary conditions to make a pipe flow i rectangular mesh?
Re: Laminar flow in pipewrong results
there is my SIF
Header
CHECK KEYWORDS Warn
Mesh DB "." "."
Include Path ""
Results Directory ""
End
Simulation
Max Output Level = 4
Coordinate System = Cartesian
Coordinate Mapping(3) = 1 2 3
Simulation Type = Steady state
Steady State Max Iterations = 100
Output Intervals = 1
Timestepping Method = BDF
BDF Order = 1
Solver Input File = case.sif
Post File = case.ep
End
Constants
Gravity(4) = 0 1 0 9.82
Stefan Boltzmann = 5.67e08
Permittivity of Vacuum = 8.8542e12
Boltzmann Constant = 1.3807e23
Unit Charge = 1.602e19
End
Body 1
Target Bodies(1) = 2
Name = "Body 1"
Equation = 1
Material = 1
End
Solver 2
Equation = NavierStokes
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 = 1.0e5
Nonlinear System Convergence Tolerance = 1.0e3
Nonlinear System Max Iterations = 20
Nonlinear System Newton After Iterations = 3
Nonlinear System Newton After Tolerance = 1.0e3
Nonlinear System Relaxation Factor = 1
Linear System Solver = Iterative
Linear System Iterative Method = BiCGStab
Linear System Max Iterations = 500
Linear System Convergence Tolerance = 1.0e3
BiCGstabl polynomial degree = 2
Linear System Preconditioning = ILU1
Linear System ILUT Tolerance = 1.0e3
Linear System Abort Not Converged = False
Linear System Residual Output = 1
Linear System Precondition Recompute = 1
End
Solver 1
Equation = Result Output
Output File Name = case
Output Format = Vtu
Procedure = "ResultOutputSolve" "ResultOutputSolver"
Exec Solver = Always
End
Equation 1
Name = "navierstokes"
Active Solvers(1) = 2
End
Equation 2
Name = "Equation 2"
Active Solvers(1) = 1
End
Material 1
Name = "Water (room temperature)"
Heat Conductivity = 0.58
Heat Capacity = 4183.0
Viscosity = 1.004e3
Sound speed = 1497.0
Heat expansion Coefficient = 0.207e3
Porosity Model = Always saturated
Relative Permittivity = 80.1
Density = 998.23
End
Boundary Condition 1
Target Boundaries(1) = 4
Name = "inlet"
Velocity 1 = 0.0385
Velocity 2 = 0.0
End
Boundary Condition 2
Target Boundaries(1) = 1
Name = "outlet"
Velocity 2 = 0.0
End
Boundary Condition 3
Target Boundaries(1) = 2
Name = "walls"
Velocity 1 = 0.0
Velocity 2 = 0.0
End
Header
CHECK KEYWORDS Warn
Mesh DB "." "."
Include Path ""
Results Directory ""
End
Simulation
Max Output Level = 4
Coordinate System = Cartesian
Coordinate Mapping(3) = 1 2 3
Simulation Type = Steady state
Steady State Max Iterations = 100
Output Intervals = 1
Timestepping Method = BDF
BDF Order = 1
Solver Input File = case.sif
Post File = case.ep
End
Constants
Gravity(4) = 0 1 0 9.82
Stefan Boltzmann = 5.67e08
Permittivity of Vacuum = 8.8542e12
Boltzmann Constant = 1.3807e23
Unit Charge = 1.602e19
End
Body 1
Target Bodies(1) = 2
Name = "Body 1"
Equation = 1
Material = 1
End
Solver 2
Equation = NavierStokes
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 = 1.0e5
Nonlinear System Convergence Tolerance = 1.0e3
Nonlinear System Max Iterations = 20
Nonlinear System Newton After Iterations = 3
Nonlinear System Newton After Tolerance = 1.0e3
Nonlinear System Relaxation Factor = 1
Linear System Solver = Iterative
Linear System Iterative Method = BiCGStab
Linear System Max Iterations = 500
Linear System Convergence Tolerance = 1.0e3
BiCGstabl polynomial degree = 2
Linear System Preconditioning = ILU1
Linear System ILUT Tolerance = 1.0e3
Linear System Abort Not Converged = False
Linear System Residual Output = 1
Linear System Precondition Recompute = 1
End
Solver 1
Equation = Result Output
Output File Name = case
Output Format = Vtu
Procedure = "ResultOutputSolve" "ResultOutputSolver"
Exec Solver = Always
End
Equation 1
Name = "navierstokes"
Active Solvers(1) = 2
End
Equation 2
Name = "Equation 2"
Active Solvers(1) = 1
End
Material 1
Name = "Water (room temperature)"
Heat Conductivity = 0.58
Heat Capacity = 4183.0
Viscosity = 1.004e3
Sound speed = 1497.0
Heat expansion Coefficient = 0.207e3
Porosity Model = Always saturated
Relative Permittivity = 80.1
Density = 998.23
End
Boundary Condition 1
Target Boundaries(1) = 4
Name = "inlet"
Velocity 1 = 0.0385
Velocity 2 = 0.0
End
Boundary Condition 2
Target Boundaries(1) = 1
Name = "outlet"
Velocity 2 = 0.0
End
Boundary Condition 3
Target Boundaries(1) = 2
Name = "walls"
Velocity 1 = 0.0
Velocity 2 = 0.0
End

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Re: Laminar flow in pipewrong results
Hi
Use "axi symmetric" coordinate system and set your mesh such that (x,y) corresponds to (r,z). This means that in your mesh x \in [0,R].
Peter
Use "axi symmetric" coordinate system and set your mesh such that (x,y) corresponds to (r,z). This means that in your mesh x \in [0,R].
Peter
Re: Laminar flow in pipewrong results
Thank You for interest. I made a mesh, like in attachment, is it correct?
 Attachments

 MESH1.jpg (130.34 KiB) Viewed 3112 times
Re: Laminar flow in pipewrong results
I think now is correct, but what boundary condition set on bottom edge (axis)?
left edge is inlet, top edge is wall, right edge is outlet
left edge is inlet, top edge is wall, right edge is outlet
 Attachments

 MESH2.jpg
 (138.62 KiB) Not downloaded yet
Re: Laminar flow in pipewrong results
I found the answer in older posts