23.2.6 Options for Spray Modeling

Select the spray model by going to the Physical Models tab in Discrete Phase Model dialog box. Two spray models are available: Droplet Collision and Droplet Breakup.

Modeling Droplet Collisions

To include the effect of droplet collisions, as described in this section in the separate Theory Guide , select the Droplet Collision option under Spray Models. There are no further inputs for this model.

Modeling Spray Breakup

To enable the modeling of spray breakup, select the Droplet Breakup option under Spray Model and then select the desired model ( TAB or Wave). A detailed description of these models can be found in this section in the separate Theory Guide.

For the TAB model, you will need to specify a value for $y_0$ (the initial distortion at time equal to zero in this equation in the separate Theory Guide) in the y0 field. The default value ( $y_0=0$) is recommended. You will also set the number of Breakup Parcels (under Breakup Constants), to split the droplet into several child parcels, as described in this section in the separate Theory Guide. The diameter of the child parcels is sampled from a Rosin-Rammler distribution. This can be switched off in the TUI with the command

/define/models/dpm/spray-modeling/randomize-tab-diameters?

For the wave model, you will need to specify values for B0 and B1, where B0 is the constant $B_0$ in this equation in the separate Theory Guide and B1 is the constant $B_1$ in this equation . You will generally not need to modify the value of B0, as the default value 0.61 is acceptable for nearly all cases. A value of 1.73 is recommended for B1.

For steady-state simulations, you will also need to specify an appropriate Particle Time Step Size and the Number of Time Steps which will control the spray density. See Section  23.2.1 for more information.

Note that you may want to use the dynamic drag law when you use one of the spray breakup models. See Section  23.2.4 for information about choosing the drag law.