Setting Initial Conditions

Set the initial conditions for the physics continuum.

Initially, the fluidized bed contains 40.2% particles and is 0.5 m deep. Before bubble formation, the particles are motionless and the air velocity sustains the fluidization of the bed. You can use field functions to set the initial volume fraction for each phase and the initial velocity of air.

To set the initial conditions:

Create the field functions for the initial volume fraction for each phase and the initial velocity of air.

  1. Define the field function for the initial particle volume fraction as follows:
    1. Right-click the Automation > Field Functions node and select New > Scalar.
    2. Rename the User Field Function 1 node to InitialVFParticle.
    3. Select the InitialVFParticle node and set the following properties:
      Property Setting
      Function Name InitialVFParticle
      Definition ($$Centroid[1] < 0.5) ? 0.402 : 1e-6
  2. Use the same procedure to create field functions for the initial air volume fraction and the initial velocity of air, using the details below:

    Name / Function Name

    Definition

    InitialVFAir

    ($$Centroid[1] < 0.5) ? 0.598 : 0.999999

    InitialVelAir

    0.25/$InitialVFAir

Set the initial conditions for the Physics 1 continuum.

  1. Edit the Continua > Physics 1 > Models > Multiphase > Phases node and set the following properties:
    Node Property Setting
    Air > Initial Conditions
    Velocity Method Composite
    Composite > Y Component Method Field Function
    Scalar Function InitialVelAir
    Volume Fraction Method Field Function
    Scalar Function InitialVFAir
    Particle > Initial Conditions
    Volume Fraction Method Field Function
    Scalar Function InitialVFParticle


  2. Save the simulation.