Importing CAD GeometryΒΆ

../_images/image164.jpg

Model Set-up

Companion Files: 500L_TANK.igs, 500L_IMP.igs

  1. Start the M-Star Build via Windows Start Menu

  2. Pre-Process -> Define Outer Geometry

    1. Open 500L_TANK.igs file

    2. Accept default orientation

    3. Accept the default origin location

    4. Specify a fluid height of 0.5 m

    5. Specify a head space of 0 m

  3. Pre-Process -> Define Moving Geometry

    1. Open 500L_IMP.igs file

    2. Accept default mount point

    3. Accept the default axis of rotation

    4. Click Next

    5. Select motion type: Rotation

    6. Select impeller speed: 60 RPM

    7. Specify placement: 0,0.2,0 m

  • To minimize additional manipulations, it is recommended that tanks and impellers enter the model with a local origin defined at (0,0,0) and aligned in the +y direction.

  • The impeller mount point defines the root of the axis of rotation. In general, this point will pass through the center of the impeller hub.

  • The axis of rotation orientation vector, which is a unit vector rooted at the impeller mount point, defines the axis about which the impeller will spin.

  • View -> Zoom Extents resets the view to show the entire model

  1. Right-click on the impeller icon and select: Rotate about X, as shown below, and enter 90 degrees. image::image166.jpg[image,width=200,height=185]

  2. Adjust the impeller reference point to (0., 0.2, -0.3), such that the impeller is near the tank sidewall and pumps in the +z direction.

  • The original impeller rotation axis, define upon geometry import, commutes will all subsequent impeller translations and rotations. It does not need to be redefined.

  1. Pre-Process -> Add Scalar Field

  2. Right-click on the Scalar Field icon and select: Add Box

  3. Select the Scalar Field icon

    1. Specify DiffusionCoefficient: 1e-9 m2/s

    2. Specify ReactionChemistry: 0

    3. Specify ScalarName: Dye

    4. Specify StartingConcentration: 0

    5. Adjust box domain as desired

    6. Specify Scalar Box Starting Concentration: 1

    7. Specify StartTime: 10 s

    8. Specify StopTime: 10 s

  • The scalar field is a continuous phase that moves in response to advection and diffusion.

  • Scalar fields can be made to react with other fields via user-defined temperature and concentration dependant reaction rates.

  • Setting an equivalent StartTime/StopTime has the effect of an instantaneous injection

  1. Select the Simulation Component

    1. Specify Resolution on Reference Length: 180

    2. Specify runtime: 180 s

    3. Specify CheckPointInterval: 30 s

    4. Specify data output: 0.05 s

    5. Specify slice output: 0.1 s

    6. Specify volume output: 0.25 s

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 species conc. tab

  • Since the system is closed, the ConcMean[mol/L] will remain constant over the simulation.

  • As the dye becomes increasing homogeneous, the ConcStdDev will decrease. This convergence can be used to quantify blend time.

  • The exposure is a measure of the instantaneous mass transfer rate.

  1. Clear the data by pressing Delete All

  2. Open the volume.txt file in ParaView

  3. Press the MStarPost3D button.

  • Animate the sequence and observe the time-evolution of the velocity and scalar fields

  • Only three dimensional scalar fields (e.g. velocity magnitude, total

    kinetic energy, species concentration) can be visualized as 3D volumes.