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Initial Condition

Initial Condition is a volume condition in the Multiphase module pertaining to selected Volumes. Initial Condition refers to the values of the independent variables used to start a simulation when the Start from Initial Values is selected in the Simulation Panel. The alternative to using Initial Condition to start a simulation are Start from Solution or Continuation Run. In such cases, the Initial Condition set under the volume are not used. The initial volume fractions of the individual components are specified for each volume as follows: Geometric Entities Panel > Volumes > [Desired Volume] Properties Panel > Model Tab > Multiphase > Component > Initial Condition The Specified Value for the Initial Condition allows to specify the initial volume fraction of a selected component in a selected volume. The sum of the Value of the initial volume fractions for all components in a volume should add to one. Expression Editor can also be used to set the initial Specified Value of the volume fraction.   Note: If the sum of the volume fractions for all components in a volume do not add to one, the program will give an error message when the simulation is started.

Figure 5.106 - Initial condition

 

In the case of a mixture, the Initial Condition is specified under the Flow module as follows:

• Geometric Entities Panel > Volumes > [Desired Volume]

• Properties Panel > Model Tab > Flow > Mixture > Initial Condition

The Initial Condition for the mixture can either be that for a rotating volume (Rotating System) or non-rotating volume (Specified Value) as explained in initial conditions for Flow module.

 

Source

A Source listing appears for a multiphase mixture under the Flow or Heat module as shown below:

• Geometric Entities Panel > Volumes > [Desired Volume]

• Properties Panel > Model Tab > Flow > Mixture > Create a New Source

or

• Geometric Entities Panel > Volumes > [Desired Volume]

• Properties Panel > Model Tab > Heat > Mixture > Create a New Source

When a source is created for the mixture under the Flow module, the possible sources are Momentum Source and Mass Source.

When a source is created for the mixture under the Heat module, the possible sources are Heat Source Per Volume and Total Heat Source.

 

State

State of a volume determines whether Mixture equation is solved (Active) or not solved (Blanked) within that volume. Specify the State of a volume as follows:

• Geometric Entities Panel > Volumes > [Desired Volume]

• Properties Panel > Model Tab > Flow > Mixture > State > [Active Multi-component Flow, Active Flow or Blanked]

or

• Geometric Entities Panel > Volumes > [Desired Volume]

• Properties Panel > Model Tab > Heat > Mixture > State > [Active Multi-component Heat, Active Heat or Blanked]