# particles leave domain

 Register Blogs Members List Search Today's Posts Mark Forums Read March 6, 2016, 03:51 particles leave domain
#1
Senior Member

Join Date: May 2012
Location: Melbourne
Posts: 161
Rep Power: 10 Hello,

why are some particles leaving the domain (see image)

Cheers,

Steffen
Attached Images particles.gif (56.0 KB, 100 views)   March 6, 2016, 17:29 #2 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 16,667 Rep Power: 130    I have no idea. If you explain what you are doing we might have some idea of how to help you. Please post your CCL and a image of your geometry.   March 7, 2016, 04:13 #3
Senior Member

Join Date: May 2012
Location: Melbourne
Posts: 161
Rep Power: 10 I just want to simulate the particle travelling time. Seems some times they dont interact with the geometry, sometimes they do
Attached Files particles fly out.zip (6.2 KB, 9 views)   March 7, 2016, 04:19 #4 Senior Member   Maxim Join Date: Aug 2015 Location: Germany Posts: 410 Rep Power: 9 sorry, I don't open *.zip files from random people from the internet Did you set the boundary conditions correctly to that surface at the bottom? Please paste your ccl in an [CODE]-Environment   March 7, 2016, 04:26 #5 Senior Member   Join Date: May 2012 Location: Melbourne Posts: 161 Rep Power: 10 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 = 15 [s] END TIME STEPS: Option = Timesteps Timesteps = 3 [s] END END DOMAIN: Default Domain Coord Frame = Coord 0 Domain Type = Fluid Location = B460 BOUNDARY: Default Domain Default Boundary Type = WALL Location = F462.460,F463.460,F464.460 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = No Slip Wall END WALL ROUGHNESS: Option = Smooth Wall END END FLUID: particle BOUNDARY CONDITIONS: PARTICLE WALL INTERACTION: Option = Equation Dependent END VELOCITY: Option = Restitution Coefficient Parallel Coefficient of Restitution = 1 Perpendicular Coefficient of Restitution = 0.8 END END END END BOUNDARY: Default Domain Inlet Boundary Type = INLET Location = Inlet BOUNDARY CONDITIONS: FLOW DIRECTION: Option = Normal to Boundary Condition END FLOW REGIME: Option = Subsonic END MASS AND MOMENTUM: Mass Flow Rate = 7 [kg s^-1] Mass Flow Rate Area = As Specified Option = Mass Flow Rate END TURBULENCE: Option = Medium Intensity and Eddy Viscosity Ratio END END FLUID: particle BOUNDARY CONDITIONS: MASS AND MOMENTUM: Normal Speed = 0.172 [m s^-1] Option = Normal Speed END PARTICLE MASS FLOW RATE: Mass Flow Rate = 0.1 [kg s^-1] END PARTICLE POSITION: Option = Uniform Injection Particle Locations = Equally Spaced NUMBER OF POSITIONS: Number per Unit Time = 100 [s^-1] Option = Direct Specification END END END END END BOUNDARY: Default Domain Outlet Boundary Type = OUTLET Location = Outlet BOUNDARY CONDITIONS: FLOW REGIME: Option = Subsonic END MASS AND MOMENTUM: Option = Average Static Pressure Pressure Profile Blend = 0.05 Relative Pressure = 0 [Pa] END PRESSURE AVERAGING: Option = Average Over Whole Outlet END END END BOUNDARY: Default Domain Symmetrie Boundary Type = SYMMETRY Location = Symmetrie END DOMAIN MODELS: BUOYANCY MODEL: Option = Non Buoyant END DOMAIN MOTION: Option = Stationary END MESH DEFORMATION: Option = None END REFERENCE PRESSURE: Reference Pressure = 1 [atm] END END FLUID DEFINITION: Fluied 1 Material = Water Option = Material Library MORPHOLOGY: Option = Continuous Fluid END END FLUID DEFINITION: particle Material = Water Option = Material Library MORPHOLOGY: Option = Dispersed Particle Transport Solid PARTICLE DIAMETER DISTRIBUTION: Maximum Diameter = 2 [mm] Mean Diameter = 1.5 [mm] Minimum Diameter = 1 [mm] Option = Normal in Diameter by Mass Standard Deviation in Diameter = 0.25 [mm] END END END FLUID MODELS: COMBUSTION MODEL: Option = None END FLUID: particle EROSION MODEL: Option = None END PARTICLE ROUGH WALL MODEL: Option = None END END HEAT TRANSFER MODEL: Fluid Temperature = 25 [C] Option = Isothermal END THERMAL RADIATION MODEL: Option = None END TURBULENCE MODEL: Option = k epsilon END TURBULENT WALL FUNCTIONS: Option = Scalable END END FLUID PAIR: Fluied 1 | particle 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 INITIALISATION: Option = Automatic INITIAL CONDITIONS: Velocity Type = Cartesian CARTESIAN VELOCITY COMPONENTS: Option = Automatic with Value U = 0 [m s^-1] V = 0 [m s^-1] W = 0 [m s^-1] END STATIC PRESSURE: Option = Automatic with Value Relative Pressure = 0 [Pa] END TURBULENCE INITIAL CONDITIONS: Option = Medium Intensity and Eddy Viscosity Ratio END END END PARTICLE INJECTION REGION: Particle Injection Region 1 Coord Frame = Coord 0 FLUID: particle INJECTION CONDITIONS: INJECTION METHOD: Option = Cone CONE DEFINITION: Injection Centre = 2 [m], 0 [m], -0.25 [m] Inner Radius of Injection Plane = 2 [cm] Option = Ring Cone Outer Radius of Injection Plane = 5 [cm] INJECTION DIRECTION: Injection Direction X Component = -2 Injection Direction Y Component = 0 Injection Direction Z Component = 0 Option = Cartesian Components END END INJECTION VELOCITY: Cone Angle = 1 [deg] Injection Velocity Magnitude = 0.172 [m s^-1] Option = Velocity Magnitude END NUMBER OF POSITIONS: Number per Unit Time = 100 [s^-1] Option = Direct Specification END END PARTICLE DIAMETER DISTRIBUTION: Diameter = 1 [mm] Option = Specified Diameter END PARTICLE MASS FLOW RATE: Mass Flow Rate = 0.007 [kg s^-1] END END END END END OUTPUT CONTROL: EXPORT RESULTS: Export Results 1 Option = Particle Track Data EXPORT FORMAT: Filename Prefix = particle track Option = CFX CSV END EXPORT FREQUENCY: Option = Every Timestep END EXPORT TRACK DATA: Option = Selected Variables Output Boundary = Default Domain Outlet Output Variables List = particle.Particle Time Particle Definition = particle END END PARTICLE TRACK FILE: Keep Track File = On Option = Specified Time Spacing Track File Format = Formatted Track Printing Interval = 1 Track Time Spacing = 20 [s] END RESULTS: File Compression Level = Default Option = Standard END TRANSIENT RESULTS: Transient Results 1 File Compression Level = Default Option = Standard OUTPUT FREQUENCY: Option = Timestep Interval Timestep Interval = 0 END END TRANSIENT RESULTS: Transient Results 2 File Compression Level = Default Option = Standard OUTPUT FREQUENCY: Option = Timestep Interval Timestep Interval = 1 END END TRANSIENT RESULTS: Transient Results 3 File Compression Level = Default Option = Standard OUTPUT FREQUENCY: Option = Every Timestep END END END SOLVER CONTROL: Turbulence Numerics = First Order ADVECTION SCHEME: Option = High Resolution END CONVERGENCE CONTROL: Maximum Number of Coefficient Loops = 20 Minimum Number of Coefficient Loops = 1 Timescale Control = Coefficient Loops END CONVERGENCE CRITERIA: Residual Target = 1.E-4 Residual Type = RMS END PARTICLE CONTROL: PARTICLE INTEGRATION: Maximum Particle Integration Time Step = 1.0E10 [s] Option = Forward Euler END PARTICLE SOURCE SMOOTHING: Option = Smooth END PARTICLE TERMINATION CONTROL: Maximum Number of Integration Steps = 2000 Maximum Tracking Distance = 15 [m] Maximum Tracking Time = 17 [s] END END TRANSIENT SCHEME: Option = Second Order Backward Euler TIMESTEP INITIALISATION: Option = Automatic END END END END   March 7, 2016, 04:28 #6 Senior Member   Join Date: May 2012 Location: Melbourne Posts: 161 Rep Power: 10 the other bit would have been the step file   March 7, 2016, 05:25 #7 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 16,667 Rep Power: 130    Your simulation time step is 3s and you have no limit to the particle tracking time step. Have you tried reducing either of these numbers? pimpa likes this.   March 7, 2016, 05:39 #8 Senior Member   Maxim Join Date: Aug 2015 Location: Germany Posts: 410 Rep Power: 9 And do you have a reason why you have set 20 as the 'Maximum Number of Coefficient Loops'? That seems quite high to me. Suggested is usually 3-5. Sometimes you need 10.   March 7, 2016, 06:01 #9 Senior Member   Join Date: May 2012 Location: Melbourne Posts: 161 Rep Power: 10 I guess its the time step, if thats a snapshot in time, the particles will not find the wall. Just wanted to reduce computing time and file size. pimpa likes this.   March 7, 2016, 16:19 #10 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 16,667 Rep Power: 130    If you set the time step size to keep the file size to a minimum then you are completely on the wrong track. Time step size must be set from the results of a sensitivity analysis where you determine what time step size you need. Likewise convergence tolerance and mesh resolution. Otherwise the result you get are rubbish. And the computing time and file size gets to whatever size it needs to, and you just need to make sure you have a computing system big enough to handle it. pimpa likes this.  Thread Tools Search this Thread Show Printable Version Email this Page Search this Thread: Advanced Search Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are Off Pingbacks are On Refbacks are On Forum Rules Similar Threads Thread Thread Starter Forum Replies Last Post Saima CFX 45 September 22, 2015 10:53 aja1345 FLUENT 0 August 5, 2015 01:51 asal FLUENT 0 March 30, 2014 10:58 Ervideiro CFX 1 June 1, 2010 09:50 diffo FLUENT 0 March 19, 2009 11:23

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