[sakurabogoda]

Hi,
I have a problem regarding particle tracking calculations of a cyclone. I am working with RSM, and using backup files, I can see particles have entered to cyclone cone region, but after that no more extension,and only can see increment of the velocity. But output file shows particle tracking.

Can anybody please describe me why this is happening like this? it is almost 5s passes and total time is 10s.

thanks...

[ghorrocks]

Are you sure you have the boundary conditions correct? The correct inlet flow, and pressures on all exit ports?

[sakurabogoda]

hi,
yes.. I have used velocity at inlet and pressure boundary condition at outlet..
One more thing is with the vector diagram, I can see flow is going out.

[ghorrocks]

Yes, but have you set the correct pressures and flow rates? If the conditions are not set correctly then the device will not function as intended, and strange things can happen - like what you are seeing.

[sakurabogoda]

hi Glenn,
Thanks a lot. But truely I cannot find a mistake with my model. I am attaching ccl file with this.
Could you pls have a look?

LIBRARY:
CEL:
EXPRESSIONS:
MFR = 2.828E-8[kg s^-1]
PR = 1E7*step(0.0001-t/1[s]) [s^-1]
END
END
MATERIAL: Air at 25 C
Material Description = Air at 25 C and 1 atm (dry)
Material Group = Air Data, Constant Property Gases
Option = Pure Substance
Thermodynamic State = Gas
PROPERTIES:
Option = General Material
EQUATION OF STATE:
Density = 1.185 [kg m^-3]
Molar Mass = 28.96 [kg kmol^-1]
Option = Value
END
SPECIFIC HEAT CAPACITY:
Option = Value
Specific Heat Capacity = 1.0044E+03 [J kg^-1 K^-1]
Specific Heat Type = Constant Pressure
END
REFERENCE STATE:
Option = Specified Point
Reference Pressure = 1 [atm]
Reference Specific Enthalpy = 0. [J/kg]
Reference Specific Entropy = 0. [J/kg/K]
Reference Temperature = 25 [C]
END
DYNAMIC VISCOSITY:
Dynamic Viscosity = 1.831E-05 [kg m^-1 s^-1]
Option = Value
END
THERMAL CONDUCTIVITY:
Option = Value
Thermal Conductivity = 2.61E-02 [W m^-1 K^-1]
END
ABSORPTION COEFFICIENT:
Absorption Coefficient = 0.01 [m^-1]
Option = Value
END
SCATTERING COEFFICIENT:
Option = Value
Scattering Coefficient = 0.0 [m^-1]
END
REFRACTIVE INDEX:
Option = Value
Refractive Index = 1.0 [m m^-1]
END
THERMAL EXPANSIVITY:
Option = Value
Thermal Expansivity = 0.003356 [K^-1]
END
END
END
MATERIAL: Particles
Material Group = Particle Solids
Option = Pure Substance
PROPERTIES:
Option = General Material
EQUATION OF STATE:
Density = 500 [kg m^-3]
Molar Mass = 1.0 [kg kmol^-1]
Option = Value
END
END
END
END
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 = 10 [s]
END
TIME STEPS:
First Update Time = 0.0 [s]
Initial Timestep = 0.00001 [s]
Option = Adaptive
Timestep Update Frequency = 1
TIMESTEP ADAPTION:
Maximum Timestep = 0.005 [s]
Minimum Timestep = 0.00001 [s]
Option = Number of Coefficient Loops
Target Maximum Coefficient Loops = 4
Target Minimum Coefficient Loops = 2
Timestep Decrease Factor = 0.8
Timestep Increase Factor = 1.06
END
END
END
DOMAIN: cyclone
Coord Frame = Coord 0
Domain Type = Fluid
Location = CREATED_MATERIAL_17,CREATED_MATERIAL_16
BOUNDARY: Box walls
Boundary Type = WALL
Location = BOX
BOUNDARY CONDITIONS:
MASS AND MOMENTUM:
Option = No Slip Wall
END
WALL ROUGHNESS:
Option = Smooth Wall
END
END
FLUID: particles
BOUNDARY CONDITIONS:
PARTICLE WALL INTERACTION:
Option = Equation Dependent
END
VELOCITY:
Option = Restitution Coefficient
Parallel Coefficient of Restitution = 1.0
Perpendicular Coefficient of Restitution = 1.0
END
END
END
END
BOUNDARY: cyclone walls
Boundary Type = WALL
Location = \
VORTEX_FINDER_1,VORTEX_FINDER_2,TOP_CAP,OULLET_TUB E,INLET_TUBE,HOPPER\
_BASE,HOPPER,BODY
BOUNDARY CONDITIONS:
MASS AND MOMENTUM:
Option = No Slip Wall
END
WALL ROUGHNESS:
Option = Smooth Wall
END
END
FLUID: particles
BOUNDARY CONDITIONS:
PARTICLE WALL INTERACTION:
Option = Equation Dependent
END
VELOCITY:
Option = Restitution Coefficient
Parallel Coefficient of Restitution = 1.0
Perpendicular Coefficient of Restitution = 1.0
END
END
END
END
BOUNDARY: inlet
Boundary Type = INLET
Location = INLET
BOUNDARY CONDITIONS:
FLOW REGIME:
Option = Subsonic
END
MASS AND MOMENTUM:
Normal Speed = 10 [m s^-1]
Option = Normal Speed
END
TURBULENCE:
Option = Medium Intensity and Eddy Viscosity Ratio
END
END
FLUID: particles
BOUNDARY CONDITIONS:
MASS AND MOMENTUM:
Normal Speed = 10 [m s^-1]
Option = Normal Speed
END
PARTICLE MASS FLOW RATE:
Mass Flow Rate = MFR
END
PARTICLE POSITION:
Option = Uniform Injection
NUMBER OF POSITIONS:
Number per Unit Time = PR
Option = Direct Specification
END
END
END
END
END
BOUNDARY: oultet
Boundary Type = OPENING
Location = OUTLET
BOUNDARY CONDITIONS:
FLOW DIRECTION:
Option = Normal to Boundary Condition
END
FLOW REGIME:
Option = Subsonic
END
MASS AND MOMENTUM:
Option = Opening Pressure and Direction
Relative Pressure = 0 [Pa]
END
TURBULENCE:
Option = Medium Intensity and Eddy Viscosity Ratio
END
END
END
DOMAIN MODELS:
BUOYANCY MODEL:
Buoyancy Reference Density = 1.2 [kg m^-3]
Gravity X Component = 0 [m s^-2]
Gravity Y Component = -9.81 [m s^-2]
Gravity Z Component = 0 [m s^-2]
Option = Buoyant
BUOYANCY REFERENCE LOCATION:
Option = Automatic
END
END
DOMAIN MOTION:
Option = Stationary
END
MESH DEFORMATION:
Option = None
END
REFERENCE PRESSURE:
Reference Pressure = 101325 [Pa]
END
END
FLUID DEFINITION: Air
Material = Air at 25 C
Option = Material Library
MORPHOLOGY:
Option = Continuous Fluid
END
END
FLUID DEFINITION: particles
Material = Particles
Option = Material Library
MORPHOLOGY:
Option = Dispersed Particle Transport Solid
PARTICLE DIAMETER DISTRIBUTION:
Maximum Diameter = 18 [micron]
Mean Diameter = 5.4519154808 [micron]
Minimum Diameter = 0.742 [micron]
Option = Normal in Diameter by Number
Standard Deviation in Diameter = 4.7494103370 [micron]
END
END
END
FLUID MODELS:
COMBUSTION MODEL:
Option = None
END
FLUID: Air
FLUID BUOYANCY MODEL:
Option = Density Difference
END
END
FLUID: particles
EROSION MODEL:
Option = None
END
FLUID BUOYANCY MODEL:
Option = Density Difference
END
PARTICLE ROUGH WALL MODEL:
Option = None
END
END
HEAT TRANSFER MODEL:
Option = None
END
THERMAL RADIATION MODEL:
Option = None
END
TURBULENCE MODEL:
Option = SSG Reynolds Stress
BUOYANCY TURBULENCE:
Option = None
END
END
TURBULENT WALL FUNCTIONS:
Option = Scalable
END
END
FLUID PAIR: Air | particles
Particle Coupling = One-way Coupling
MOMENTUM TRANSFER:
DRAG FORCE:
Option = Schiller Naumann
END
PRESSURE GRADIENT FORCE:
Option = None
END
TURBULENT DISPERSION FORCE:
Option = None
END
VIRTUAL MASS FORCE:
Option = None
END
END
END
END
OUTPUT CONTROL:
MONITOR OBJECTS:
MONITOR BALANCES:
Option = Full
END
MONITOR FORCES:
Option = Full
END
MONITOR PARTICLES:
Option = Full
END
MONITOR POINT: point1
Cartesian Coordinates = -0.1305 [m], 0.21944 [m], 0 [m]
Option = Cartesian Coordinates
Output Variables List = Velocity,Velocity u,Velocity v,Velocity w
END
MONITOR POINT: point2
Cartesian Coordinates = 0.0[m],0.0[m],0.0[m]
Option = Cartesian Coordinates
Output Variables List = Velocity,Velocity u,Velocity v,Velocity w
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
Option = Standard
OUTPUT FREQUENCY:
Option = Time Interval
Time Interval = 1 [s]
END
END
TRANSIENT STATISTICS: velocity max
Option = Maximum
Output Variables List = Velocity
END
TRANSIENT STATISTICS: velocity min
Option = Maximum
Output Variables List = Velocity
END
TRANSIENT STATISTICS: velocity rms
Option = Root Mean Square
Output Variables List = Velocity
END
TRANSIENT STATISTICS: velocity std
Option = Standard Deviation
Output Variables List = Velocity
END
END
SOLVER CONTROL:
Turbulence Numerics = First Order
ADVECTION SCHEME:
Option = High Resolution
END
CONVERGENCE CONTROL:
Maximum Number of Coefficient Loops = 5
Minimum Number of Coefficient Loops = 1
Timescale Control = Coefficient Loops
END
CONVERGENCE CRITERIA:
Residual Target = 0.00001
Residual Type = RMS
END
PARTICLE CONTROL:
PARTICLE INTEGRATION:
Option = Forward Euler
END
PARTICLE TERMINATION CONTROL:
Maximum Number of Integration Steps = 1000000
Maximum Tracking Distance = 10000 [m]
Maximum Tracking Time = 10 [s]
END
END
TRANSIENT SCHEME:
Option = Second Order Backward Euler
TIMESTEP INITIALISATION:
Lower Courant Number = 0.00001
Option = Automatic
Upper Courant Number = 1
END
END
END
END
COMMAND FILE:
Version = 14.0
Results Version = 14.0
END
SIMULATION CONTROL:
EXECUTION CONTROL:
EXECUTABLE SELECTION:
Double Precision = Yes
END
PARALLEL HOST LIBRARY:
HOST DEFINITION: node01.local
Installation Root = /ansys_inc/v%v/CFX
Host Architecture String = linux-amd64
END
HOST DEFINITION: node02.local
Installation Root = /ansys_inc/v%v/CFX
Host Architecture String = linux-amd64
END
HOST DEFINITION: node03.local
Host Architecture String = linux-amd64
Installation Root = /ansys_inc/v%v/CFX
END
END
PARTITIONER STEP CONTROL:
MEMORY CONTROL:
Memory Allocation Factor = 1.2
END
PARTITIONING TYPE:
Option = MeTiS
MeTiS Type = k-way
Partition Size Rule = Automatic
Partition Weight Factors = 0.03030, 0.03030, 0.03030, 0.03030, \
0.03030, 0.03030, 0.03030, 0.03030, 0.03030, 0.03030, 0.03030, \
0.03030, 0.03030, 0.03030, 0.03030, 0.03030, 0.03030, 0.03030, \
0.03030, 0.03030, 0.03030, 0.03030, 0.03030, 0.03030, 0.03030, \
0.03030, 0.03030, 0.03030, 0.03030, 0.03030, 0.03030, 0.03030, \
0.03030
END
END
RUN DEFINITION:
Solver Input File = /home/sganegama2/mul10/mul10_2/M10.def
Run Mode = Full
INITIAL VALUES SPECIFICATION:
INITIAL VALUES CONTROL:
Use Mesh From = Solver Input File
Continue History From = Initial Values 1
END
INITIAL VALUES: Initial Values 1
Option = Results File
File Name = /home/sganegama2/cy10ms/10msS_001.res
END
END
END
SOLVER STEP CONTROL:
Runtime Priority = Standard
MEMORY CONTROL:
Memory Allocation Factor = 5
END
PARALLEL ENVIRONMENT:
Start Method = MPICH Distributed Parallel
Parallel Host List = node03.local*11,node02.local*11,node01.local*11
END
END
END
END

[ghorrocks]

No, I do not think you understand my point. A cyclone will only work properly if the inlets and outlets are set to the correct pressures and flows. In this case you do not appear to either two outlets, you only have one. You need a clean exit at the top and a dirty exit at the bottom.

http://en.wikipedia.org/wiki/Cyclonic_separation

[sakurabogoda]

Really?? I thought, according to practical, there is a dust collection hopper at base and I have used same way..
Is it a must to use a outlet/opening at the bottom? which BC is better?

many thanks..

[ghorrocks]

Rather than guessing, how about you do some research on cyclone design (the link I posted is a good starting point) so you know how to design a good cyclone for your situation? That would seem to be the way forwards to me.