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December 4, 2013, 06:13 
particle tracking

#1 
Senior Member
S.Bogoda
Join Date: Jul 2012
Posts: 133
Rep Power: 12 
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... 

December 4, 2013, 07:24 

#2 
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Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
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Are you sure you have the boundary conditions correct? The correct inlet flow, and pressures on all exit ports?


December 4, 2013, 08:50 

#3 
Senior Member
S.Bogoda
Join Date: Jul 2012
Posts: 133
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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. 

December 4, 2013, 17:36 

#4 
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Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,263
Rep Power: 136 
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.


December 4, 2013, 22:49 

#5 
Senior Member
S.Bogoda
Join Date: Jul 2012
Posts: 133
Rep Power: 12 
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 = 2.828E8[kg s^1] PR = 1E7*step(0.0001t/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 = 1.831E05 [kg m^1 s^1] Option = Value END THERMAL CONDUCTIVITY: Option = Value Thermal Conductivity = 2.61E02 [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 = Oneway 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 = linuxamd64 END HOST DEFINITION: node02.local Installation Root = /ansys_inc/v%v/CFX Host Architecture String = linuxamd64 END HOST DEFINITION: node03.local Host Architecture String = linuxamd64 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 = kway 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 

December 4, 2013, 23:50 

#6 
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,263
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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 

December 5, 2013, 00:09 

#7 
Senior Member
S.Bogoda
Join Date: Jul 2012
Posts: 133
Rep Power: 12 
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.. 

December 5, 2013, 00:12 

#8 
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,263
Rep Power: 136 
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.


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