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-   -   sliding mesh problem in CFX (http://www.cfd-online.com/Forums/cfx/79605-sliding-mesh-problem-cfx.html)

Saima August 28, 2010 06:50

sliding mesh problem in CFX
 
Hi All,

There is a tutorial in Fluent "Tutorial 11: Using Sliding Meshes " 2D Tutorial. In fluent problem Fluid phase Velosity (which is given in Fluent around y= -Vx) imposeed under Setup => Cell Zone Conditions.

I want to do same in CFX but i have not foung Fluid Translation in CFX. How can i do it? CFX just have "Rotaion" and stationary" option in "domain"option.

I dont want to give rotaion brcause i am working on airfoil.

Please let me know.

Thank you,

ghorrocks August 29, 2010 18:59

To do anything but rotation you need to use general moving mesh. Translating mesh is meant to be a beta feature but I have never used it and cannot guarantee it works - talk to CFX support if this is of interest.

alinik April 15, 2014 13:13

Saima,

Did you succeed to translate the mesh?

I am looking into almost the same problem.

alinik April 28, 2014 12:16

Saima? did u solve it?

ghorrocks April 28, 2014 18:16

These posts are 4 years old, it is unlikely you will get any response except from the tragics like me :)

But my post from 4 years ago still stands - use moving mesh to do it.

alinik April 28, 2014 19:37

Glenn,

In all of the posts that there has been some issue with translational mesh motion you said that it is possible and yes it is. But there is one problem.
you see in my case there are two domains, one stationary, the other one is supposed to translate(not rotating, translating)
for the time steps that the interfaces of the two domains are not overlapping 100%, the solver assumes there is a wall for the non-overlapping area. Unlike the "transient rotor stator" interface. It seems that CFX can only do the sliding mesh for rotational cases not translational cases.
Now do you have any knowledge that this problem can be overcome. Maybe I can use CFX to implement translationan sliding mesh??

Thanks,

Ali

ghorrocks April 28, 2014 19:57

This interface connecting a domain with moving mesh (for translational motion) to a stationary domain works fine. You need to use transient rotor/stator interface setting.

CFX can handle translational interfaces fine. It is not restricted to rotational interfaces.

alinik April 29, 2014 10:56

Are you sure? Have you done it yourself? Because when I do that I receive an error. Also When I specify transient rotor-stator interface it asks for the axis of rotation.

singer1812 April 29, 2014 15:11

We are sure. Have done it thousands of times. What error are you getting? What kind of behavior do you want for non-overlapping interfaces?

alinik April 29, 2014 17:58

This is the error that I get.

+--------------------------------------------------------------------+
| ERROR #004100018 has occurred in subroutine FINMES.|
| Message: |
| Fatal overflow in linear solver. |
+--------------------------------------------------------------------+

Here I also have attached the CCL. Please take a look.

Thanks,

alinik April 29, 2014 17:59

# State file created: 2014/04/29 15:32:12
# CFX-15.0 build 2013.10.10-08.49-130242

FLOW: Flow Analysis 1
SOLUTION UNITS:
Angle Units = [rad]
Length Units = [m]
Mass Units = [kg]
Solid Angle Units = [sr]
Temperature Units = [K]
Time Units = [s]
END
ANALYSIS TYPE:
Option = Transient
EXTERNAL SOLVER COUPLING:
Option = None
END
INITIAL TIME:
Option = Automatic with Value
Time = 0 [s]
END
TIME DURATION:
Option = Total Time
Total Time = 1.5 [s]
END
TIME STEPS:
Option = Timesteps
Timesteps = 0.005 [s]
END
END
DOMAIN: Default Domain
Coord Frame = Coord 0
Domain Type = Fluid
Location = BODY
BOUNDARY: Domain Interface 1 Side 1
Boundary Type = INTERFACE
Location = PER_1
BOUNDARY CONDITIONS:
MASS AND MOMENTUM:
Option = Conservative Interface Flux
END
MESH MOTION:
Option = Conservative Interface Flux
END
TURBULENCE:
Option = Conservative Interface Flux
END
END
END
BOUNDARY: Domain Interface 1 Side 2
Boundary Type = INTERFACE
Location = PER_2
BOUNDARY CONDITIONS:
MASS AND MOMENTUM:
Option = Conservative Interface Flux
END
MESH MOTION:
Option = Conservative Interface Flux
END
TURBULENCE:
Option = Conservative Interface Flux
END
END
END
BOUNDARY: Domain Interface 2 Side 1
Boundary Type = INTERFACE
Location = INLET
BOUNDARY CONDITIONS:
MASS AND MOMENTUM:
Option = Conservative Interface Flux
END
MESH MOTION:
Option = Unspecified
END
TURBULENCE:
Option = Conservative Interface Flux
END
END
END
BOUNDARY: out
Boundary Type = OUTLET
Location = OUTLER
BOUNDARY CONDITIONS:
FLOW REGIME:
Option = Subsonic
END
MASS AND MOMENTUM:
Option = Static Pressure
Relative Pressure = 0 [Pa]
END
MESH MOTION:
Option = Stationary
END
END
END
BOUNDARY: pressure surface
Boundary Type = WALL
Location = PS
BOUNDARY CONDITIONS:
MASS AND MOMENTUM:
Option = No Slip Wall
Wall Velocity Relative To = Mesh Motion
END
MESH MOTION:
Option = Stationary
END
WALL ROUGHNESS:
Option = Smooth Wall
END
END
END
BOUNDARY: suction suface
Boundary Type = WALL
Location = SS
BOUNDARY CONDITIONS:
MASS AND MOMENTUM:
Option = No Slip Wall
Wall Velocity Relative To = Mesh Motion
END
MESH MOTION:
Option = Stationary
END
WALL ROUGHNESS:
Option = Smooth Wall
END
END
END
BOUNDARY: symmetric back
Boundary Type = SYMMETRY
Location = SYM1
BOUNDARY CONDITIONS:
MESH MOTION:
Option = Unspecified
END
END
END
BOUNDARY: symmetric front
Boundary Type = SYMMETRY
Location = SYM2
BOUNDARY CONDITIONS:
MESH MOTION:
Option = Unspecified
END
END
END
DOMAIN MODELS:
BUOYANCY MODEL:
Option = Non Buoyant
END
DOMAIN MOTION:
Option = Stationary
END
MESH DEFORMATION:
Displacement Relative To = Previous Mesh
Option = Regions of Motion Specified
MESH MOTION MODEL:
Option = Displacement Diffusion
MESH STIFFNESS:
Option = Increase near Small Volumes
Stiffness Model Exponent = 10
REFERENCE VOLUME:
Option = Mean Control Volume
END
END
END
END
REFERENCE PRESSURE:
Reference Pressure = 1 [atm]
END
END
FLUID DEFINITION: Fluid 1
Material = Air at 25 C
Option = Material Library
MORPHOLOGY:
Option = Continuous Fluid
END
END
FLUID MODELS:
COMBUSTION MODEL:
Option = None
END
HEAT TRANSFER MODEL:
Option = None
END
THERMAL RADIATION MODEL:
Option = None
END
TURBULENCE MODEL:
Option = k omega
END
TURBULENT WALL FUNCTIONS:
Option = Automatic
END
END
END
DOMAIN: Domain 1
Coord Frame = Coord 0
Domain Type = Fluid
Location = BODY 2
BOUNDARY: Domain Interface 2 Side 1 1
Boundary Type = INTERFACE
Location = FAM2
BOUNDARY CONDITIONS:
MASS AND MOMENTUM:
Option = Conservative Interface Flux
END
MESH MOTION:
Option = Unspecified
END
TURBULENCE:
Option = Conservative Interface Flux
END
END
END
BOUNDARY: Domain Interface 3 Side 1
Boundary Type = INTERFACE
Location = PER1
BOUNDARY CONDITIONS:
MASS AND MOMENTUM:
Option = Conservative Interface Flux
END
MESH MOTION:
Option = Conservative Interface Flux
END
TURBULENCE:
Option = Conservative Interface Flux
END
END
END
BOUNDARY: Domain Interface 3 Side 2
Boundary Type = INTERFACE
Location = PER2
BOUNDARY CONDITIONS:
MASS AND MOMENTUM:
Option = Conservative Interface Flux
END
MESH MOTION:
Option = Conservative Interface Flux
END
TURBULENCE:
Option = Conservative Interface Flux
END
END
END
BOUNDARY: in
Boundary Type = INLET
Location = FAM1
BOUNDARY CONDITIONS:
FLOW REGIME:
Option = Subsonic
END
MASS AND MOMENTUM:
Option = Cartesian Velocity Components
U = Vinx
V = Viny
W = 0 [m s^-1]
END
MESH MOTION:
Option = Stationary
END
TURBULENCE:
Fractional Intensity = 0.019
Option = Intensity and Auto Compute Length
END
END
END
BOUNDARY: rod 1
Boundary Type = WALL
Location = ROD1,ROD2
BOUNDARY CONDITIONS:
MASS AND MOMENTUM:
Option = No Slip Wall
Wall Velocity Relative To = Mesh Motion
END
MESH MOTION:
Option = Stationary
END
WALL ROUGHNESS:
Option = Smooth Wall
END
END
END
BOUNDARY: sym 1
Boundary Type = SYMMETRY
Location = SYM1 2
BOUNDARY CONDITIONS:
MESH MOTION:
Option = Unspecified
END
END
END
BOUNDARY: sym 2
Boundary Type = SYMMETRY
Location = SYM2 2
BOUNDARY CONDITIONS:
MESH MOTION:
Option = Unspecified
END
END
END
DOMAIN MODELS:
BUOYANCY MODEL:
Option = Non Buoyant
END
DOMAIN MOTION:
Option = Stationary
END
MESH DEFORMATION:
Displacement Relative To = Previous Mesh
Option = Regions of Motion Specified
MESH MOTION MODEL:
Option = Displacement Diffusion
MESH STIFFNESS:
Option = Increase near Small Volumes
Stiffness Model Exponent = 2.0
REFERENCE VOLUME:
Option = Mean Control Volume
END
END
END
END
REFERENCE PRESSURE:
Reference Pressure = 1 [atm]
END
END
FLUID DEFINITION: Fluid 1
Material = Air at 25 C
Option = Material Library
MORPHOLOGY:
Option = Continuous Fluid
END
END
FLUID MODELS:
COMBUSTION MODEL:
Option = None
END
HEAT TRANSFER MODEL:
Option = None
END
THERMAL RADIATION MODEL:
Option = None
END
TURBULENCE MODEL:
Option = k omega
END
TURBULENT WALL FUNCTIONS:
Option = Automatic
END
END
SUBDOMAIN: Subdomain 1
Coord Frame = Coord 0
Location = BODY 2
MESH MOTION:
Option = Specified Displacement
DISPLACEMENT:
Displacement X Component = 00 [m]
Displacement Y Component = 0.1 [m]*Time This Run/1 [s]
Displacement Z Component = 0 [m]
Option = Cartesian Components
END
END
END
END
DOMAIN INTERFACE: Domain Interface 1
Boundary List1 = Domain Interface 1 Side 1
Boundary List2 = Domain Interface 1 Side 2
Interface Type = Fluid Fluid
INTERFACE MODELS:
Option = Translational Periodicity
MASS AND MOMENTUM:
Option = Conservative Interface Flux
MOMENTUM INTERFACE MODEL:
Option = None
END
END
END
MESH CONNECTION:
Option = GGI
END
END
DOMAIN INTERFACE: Domain Interface 2
Boundary List1 = Domain Interface 2 Side 1 1
Boundary List2 = Domain Interface 2 Side 1
Interface Type = Fluid Fluid
INTERFACE MODELS:
Option = General Connection
FRAME CHANGE:
Option = Transient Rotor Stator
END
MASS AND MOMENTUM:
Option = Conservative Interface Flux
MOMENTUM INTERFACE MODEL:
Option = None
END
END
PITCH CHANGE:
Option = Automatic
AXIS DEFINITION:
Option = Coordinate Axis
Rotation Axis = Coord 0.3
END
END
END
MESH CONNECTION:
Option = GGI
END
END
DOMAIN INTERFACE: Domain Interface 3
Boundary List1 = Domain Interface 3 Side 1
Boundary List2 = Domain Interface 3 Side 2
Interface Type = Fluid Fluid
INTERFACE MODELS:
Option = Translational Periodicity
MASS AND MOMENTUM:
Option = Conservative Interface Flux
MOMENTUM INTERFACE MODEL:
Option = None
END
END
END
MESH CONNECTION:
Option = Automatic
END
END
INITIALISATION:
Option = Automatic
INITIAL CONDITIONS:
Velocity Type = Cartesian
CARTESIAN VELOCITY COMPONENTS:
Option = Automatic with Value
U = 3.074848454 [m s^-1]
V = -2.153036289 [m s^-1]
W = 0 [m s^-1]
END
STATIC PRESSURE:
Option = Automatic with Value
Relative Pressure = 20 [Pa]
END
TURBULENCE INITIAL CONDITIONS:
Option = Medium Intensity and Eddy Viscosity Ratio
END
END
END
OUTPUT CONTROL:
MONITOR OBJECTS:
MONITOR BALANCES:
Option = Full
END
MONITOR FORCES:
Option = Full
END
MONITOR PARTICLES:
Option = Full
END
MONITOR RESIDUALS:
Option = Full
END
MONITOR TOTALS:
Option = Full
END
END
RESULTS:
File Compression Level = Default
Option = Standard
END
TRANSIENT RESULTS: Transient Results 1
File Compression Level = Default
Include Mesh = On
Option = Selected Variables
Output Variables List = Absolute Pressure,Courant \
Number,Density,Dynamic Viscosity,Eddy \
Viscosity,Pressure,Velocity,Wall Shear,Velocity u,Velocity w,Velocity \
v,Vorticity X,Vorticity Y,Vorticity Z,Wall Shear X,Wall Shear Y,Wall \
Shear Z,Yplus,Wall Normal Velocity,Total Pressure,Turbulence Eddy \
Dissipation,Turbulence Eddy Frequency,Turbulence Kinetic Energy,Total \
Mesh Displacement X,Total Mesh Displacement Y,Total Mesh Displacement \
Z,Mesh Displacement X,Mesh Displacement Y,Mesh Displacement Z,Mesh \
Velocity X,Mesh Velocity Y,Mesh Velocity Z,Boundary Scale,Boundary \
Distance,Mesh Displacement,Mesh Expansion Factor,Orthogonality \
Angle,Orthogonality Angle Minimum,Orthogonality Factor,Orthogonality \
Factor Minimum
OUTPUT FREQUENCY:
Option = Every Timestep
END
END
TRANSIENT STATISTICS: Transient Statistics 1
Option = Arithmetic Average
Output Variables List = Absolute Pressure,Density,Pressure,Total \
Pressure,Velocity,Velocity Correlation,Vorticity,Yplus,Velocity \
Correlation ww,Vorticity X,Vorticity Y,Vorticity Z,Lighthill Stress \
vw,Lighthill Stress ww,Velocity Correlation uu,Velocity Correlation \
uv,Velocity Correlation uw,Velocity Correlation vv,Velocity \
Correlation vw,Boundary Scale,Dynamic Viscosity,Eddy \
Viscosity,Courant Number,Boundary Distance,Mesh \
Displacement,Orthogonality Factor,Orthogonality Angle \
Minimum,Orthogonality Factor Minimum,Orthogonality Angle,Total Mesh \
Displacement,Total Centroid Displacement,Turbulence Eddy \
Dissipation,Turbulence Eddy Frequency,Turbulence Kinetic Energy,Wall \
Shear
END
END
SOLVER CONTROL:
Turbulence Numerics = High Resolution
ADVECTION SCHEME:
Option = Upwind
END
CONVERGENCE CONTROL:
Maximum Number of Coefficient Loops = 10
Minimum Number of Coefficient Loops = 1
Timescale Control = Coefficient Loops
END
CONVERGENCE CRITERIA:
Residual Target = 0.000001
Residual Type = RMS
END
EQUATION CLASS: continuity
ADVECTION SCHEME:
Option = Upwind
END
END
EQUATION CLASS: ke
ADVECTION SCHEME:
Option = High Resolution
END
END
EQUATION CLASS: momentum
ADVECTION SCHEME:
Option = Upwind
END
END
EQUATION CLASS: tef
ADVECTION SCHEME:
Option = High Resolution
END
END
INTERRUPT CONTROL:
INTERRUPT CONDITION: Interrupt Condition 1
Logical Expression = remeshingcond
Option = Logical Expression
END
END
INTERSECTION CONTROL:
Option = Direct
Permit No Intersection = On
END
TRANSIENT SCHEME:
Option = First Order Backward Euler
END
END
EXPERT PARAMETERS:
degeneracy check tolerance = 1.e-2
tbulk for htc = 298
topology estimate factor = 1.8
vector parallel tolerance = 15
END
END
COMMAND FILE:
Version = 15.0
END

ghorrocks April 30, 2014 00:50

You have a velocity specified inlet with an incompressible fluid, and you have talked about an interface opening and shutting. If fluid is forced to flow in the inlet and it is not connected to the outlet and has nowhere else to go then you will crash with an overflow error.

alinik April 30, 2014 10:55

Glenn,

Thanks but what is your suggestion exactly?
I mean how else I am supposed to define the problem? specify pressure at the inlet and mass flow at the outlet?
why it does not work in this way?

singer1812 April 30, 2014 11:01

When there is no outlet, you are trying to compress the air. Since you are using incompressible air for the fluid, this wont work.

Either switch to air ideal gas (and you will have to deal with the internal shocks), or put an outlet somewhere in your model.

alinik April 30, 2014 11:05

there is an outlet at the end of second domain. the flow is coming in from the inlet and is supposed to go through the interface and enter the second one and then exit from the outlet in the second domain. Will it work?

singer1812 April 30, 2014 11:09

From your posts, it seemed that for some period of time, your interfaces are not connect. I assume they start off not connected and slide together to connect, thus allowing flow.

During the time they are not connected, you have the situation I described above, with the inlet not seeing any outlet and you are trying to compress the air.

So, no, the way you have it set up now will not work.

alinik April 30, 2014 11:55

1 Attachment(s)
Thanks for the info

you can see the both domains in this picture. The left (tiny) one is supposed to move and the other one is supposed to be stationary. The interfaces are initially 100
% overlapping but after time the overlapping part reduces.
Inlet is "velocity inlet" and "pressure" at the outlet is specified. at the very end of the simulation the areas are still overlapping(maybe about 10%) but the fact is the periodic boundary conditions specified on both domains for top and bottom surfaces and also having TRS interface should prevent that problem that you are saying. Isn't it?

singer1812 April 30, 2014 11:59

OK this is a bit different than I described.

When are you getting your error? First iteration?

alinik April 30, 2014 12:05

No, it happens after a while. Like maybe after 15 minutes

alinik April 30, 2014 12:16

1 Attachment(s)
after 50th timestep


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