Free Surface DynamicsΒΆ


Model set-up

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

  2. Build -> Define Outer Geometry

    1. Choose: Cylindrical Tank

    2. Specify tank diameter: 1.0 m

    3. Specify tank side wall height: 1.0 m

    4. Specify bottom shape: Dish

    5. Specify floor depth: 0.1 m

    6. Specify baffle count: 2

    7. Specify baffle length: 0.05 m

    8. Specify fluid height: 0.6 m

    9. Specify head space: 0.1 m

  3. Pre-Process -> Define Moving Geometry

    1. Choose: Pitch Blade Impeller

    2. Specify impeller diameter: 0.35 m

    3. Specify shaft length: 0 m

    4. Specify blade angle: 45 degrees

    5. Specify impeller speed: 120 RPM

    6. Specify impeller start-up ramp: 0 s

  • Specifying a head space greater than zero activates the free surface algorithm

  • The head space only needs to be large enough to capture sloshing.

  • The system here is intentionally under-baffled

  1. Select the Simulation Component

    1. Specify Resolution on Reference Length: 120

    2. Specify runtime: 60 s

    3. Specify CheckPointInterval: 10 s

    4. Specify data output: 0.05 s

    5. Specify slice output: 0.1 s

    6. Specify volume output: 1 s


For low tip speed systems (<2 m/s), a smaller timestep may be required to maintain interface stability. Adjust the timestep by lowering the Courant number to 0.075. The default value for closed systems is 0.1. For more information regarding the Courant number see the simulation parameters section

Model Execution

  1. Solve -> Run Solver

    1. Choose an appropriate output location

    2. Specify an appropriate number of cores

  2. File -> Save As

    1. Save your model with an appropriate name as a .3dm file

Model Post Processing

  1. Start M-Star Post via Windows Start Menu

  2. Browse to your output directory

  3. Open the slices.txt in ParaView

  4. Press the MStarPost button.

  5. Press the play button to animate the sequence

  6. The interface is illurated as an STL, which can be colored and rendered per user need.


Consider changing Background Color in the properties window to white. This can make saved images and movies more visually appealing and well suited for distribution on a variety of mediums.