Particle Blending and Suspension Modeling


Model Set-up

  1. Start the M-Star Pre-Processor via Windows Start Menu

  2. Pre-Process -> Define Outer Geometry -> Cylinder

    1. Specify tank diameter: 1.0 m

    2. Specify tank side wall height: 1.0 m

    3. Specify bottom shape: Dish

    4. Specify floor depth: 0.1 m

    5. Specify baffle count: 4

    6. Specify baffle length: 0.05 m

    7. Specify fluid height: 1 m

    8. Specify head space: 0. m

  3. Pre-Process -> Generate Moving Geometry -> Pitch

    1. Specify impeller diameter: 0.35 m

    2. Specify shaft length: 0 m

    3. Specify blade angle: 45 degrees

    4. Specify impeller speed: 60 RPM

    5. Specify impeller start-up ramp: 0 s

  4. Pre-Process -> Add Particles

    1. Set the lower corner of the bounding box to: -0.075m, 0.68m, -0.075m

    2. Set the upper corner of the bounding box to: 0.075m, 0.83m, 0.075m

    3. Choose box type: Dump

    4. Specify particle diameter: 0.0002 m

    5. Specify particle density: 2200 kg/m^3

    6. Specify particle start time: 0 s

    7. Set Particle Number Density: 100,000

  • The particle number density is the number of particles to be dumped into the box

  • Particles either a zero density or a zero diameter are massless tracers

  • Particles with non-zero density and non-zero diameter are affected by gravity and drag

  • Multiple boxes can be defined, with independent functions and particle properties

  1. Pre-Process -> Compute Tank Blend Time

    1. Specify NumberBinsX: 1

    2. Specify NumberBinsY: 10

    3. Specify NumberBinsZ: 1

    4. Specify NumberOfParticles: 50000

    5. Specify ParticleDiameter: 0 m

    6. Specify ParticleSG: 0 m

    7. Specify StartTime: 10 s


  • By default, the auto blend calculation particle injection point is 5 cm below the fluid height

  • The bin number defines the array of sub-volumes to be created across the domain

  • Increasing the number of particles increases the precision of the blend time estimate

  • The Start Time defines the time at which to begin the blend time calculation.

  1. Select the Simulation Component

    1. Specify Resolution on Reference Length: 120

    2. Specify runtime: 60 s

    3. Specify Check Point Interval: 30 s

    4. Specify Data Output Interval: 0.05 s

    5. Specify Slice Output Interval: 0.1 s

    6. Specify Volume Output: 1 s


Make sure that the runtime is sufficient to capture the blending process

Model Execution

  1. Solve -> Run Solver

    1. Choose an appropriate output location

    2. Specify an appropriate number of cores

Model Post Processing

  1. Start M-Star Post via Windows Start Menu

  2. Browse to your output directory in Windows

  3. Open the slices.txt in ParaView

  4. Press the MStarPost button.

  5. Press the green play button to animate the flow and particles.

  6. Press the AutoBlendTime tab

  • The blending COV should converge to 1.0 as the system becomes homogenized

  • The raw, bin-specific particle concentrations used to compute the blendtime are accessible in the /out/autoblendtime directory.

  • For some system geometries, the top and bottom-most bins will contain only a small quantity of fluids and should be ignored from the calculation.

  • The absolute number of particles in each bin, along with the volume of fluid in each bin, are printed to the autoBlendtimeParticles.dat and the autoBlendtimeFluid.dat files in autoblendtime output directory.

  1. Press the 3D view tab

  2. Press the play button to animate the sequence

  • If no tank or impeller is visible, try pressing the Zoom to Data button image145

  • Make the tank semi-transparent by selecting it from the browser and changing the Opacity to 0.1

  • Select the particles_ file group from browser and press the Glyph button: image148

  • The particle color can be adjusted to match speed, particle source, age, and ID.

  • The colorbar text/font is adjusted by clicking image153 , the colorbar is hidden with: image154

  • Change the view from 2D to 3D by pressing the 3D button

  • The particle movie frame rate is equal to the slice output frequency (0.1 s in this case).

  • Press the eyelid icon next to each pipeline item to show/hide various components