Nozzle
Use the Nozzle feature to release a spray of liquid droplets.
To use the Nozzle feature, the following prerequisites must be met:
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Newtonian or Newtonian, first order must be selected from the Formulation list in the physics interface Particle Release and Propagation section.
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Specify release times must be selected from the Particle release specification list in the physics interface Particle Release and Propagation section.
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Either Specify particle diameter or Specify particle mass must be selected from the Particle size distribution list in the physics interface Additional Variables section. Furthermore, the Enable macroparticles check box must be selected.
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Liquid droplets/bubbles must be selected from the Particle type list in the settings window for at least one Particle Properties node.
The Nozzle feature is supported on two geometric entity levels. If it is added as a global feature (similar to the Release from Grid feature), the initial position of the injected droplets can be specified by entering a list of coordinates. If it is added as a 0D feature (similar to the Release from Point feature), the initial positions of the injected droplets correspond to the selected points in the geometry.
Go to Release for information about the following sections: Released Particle Properties, Initial Value of Auxiliary Dependent Variables, and Advanced Settings.
Release Times
Enter values for the Release times (SI unit: s). By default the text field contains the times 0 and 1 ms. At least two release times must be specified, and the release times must increase monotonically. This is because the time intervals between successive release times are used to assign appropriate number multiplication factors to the released particles so that the mass flow rate is constant in a finite time interval.
Initial Velocity
Select an option from the Velocity specification list: From mass flow rate (the default), From change in pressure, From injection pressure, or User defined.
For From mass flow rate enter a value or expression for the Mass flow rate (SI unit: kg/s). The default is 1 g/s.
For From change in pressure enter a value or expression for the Change in pressure Δp (SI unit: N/m2). The default value is 1 MPa. Then enter a value or expression for the Discharge coefficient cd (dimensionless). The default value is 0.7.
For From injection pressure enter a value or expression for the Injection pressure pinj (SI unit: N/m2). The default value is 1 MPa. Then enter a value or expression for the Discharge coefficient cd (dimensionless). The default value is 0.7.
For User defined enter a value or expression for the Initial droplet velocity magnitude U0 (SI unit: m/s). The default value is 100 m/s.
Injection Parameters
Specify the initial droplet positions based on space dimension (qx,0, qy,0, and qz,0 for 3D components) or click the Range button () to select and define a range of specific coordinates.
Select an option from the Injector Location list: All combinations (the default) or Specified combinations. If Specified combinations is selected, the number of initial coordinates entered for each space dimension must be equal, and the total number of release positions is equal to the length of one of the lists of initial coordinates. If All combinations is selected, the total number of release positions is equal to the product of the lengths of each list of initial coordinates.
For example, suppose a 2D component includes a Nozzle node with the following initial coordinates:
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 qx,0 = range(0,1,3)
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 qy,0 = range(2,2,8)
If All combinations is selected, a total of 16 initial positions will be released, including every possible combination of the initial x- and y-coordinates. If Specified combinations is selected, particles will only be released at 4 initial positions (0,2), (1,4), (2,6), and (3,8).
The position for any particles with initial coordinates outside the geometry are set to NaN, so the particles do not appear when plotted during postprocessing.
If the Nozzle feature is added as a 0D feature (similar to the Release from Point feature), the Injector location list and the text fields for the initial coordinates are not shown, and the initial coordinates are instead specified by selecting points in the geometry.
Enter coordinates for the Injector axis r (dimensionless) based on space dimension. By default the injector axis points in the positive x direction.
Enter a value or expression for the Nozzle exit radius r0 (SI unit: m), which determines the initial size of released droplets.
Enter a value or expression for the Number of parcels per release N0 (dimensionless).
The Number of parcels per release does not actually restrict the number of droplets or the total mass of fluid that can be released by the Nozzle feature; it only restricts the number of model particles that can be released. Each model particle represents a parcel representing an arbitrary number of droplets. The number of droplets per model particle is always available as an auxiliary dependent variable because the Enable macroparticles check box must be selected in the physics interface Additional Variables section in order to use this feature.
Maximum Cone Angle
Select an option from the Maximum cone angle specification list: User defined (the default) or From Kelvin-Helmholtz instability model.
If User defined is selected, enter a value or expression for the Maximum cone angle Θ (SI unit: rad). The default value is 10°.
If From Kelvin-Helmholtz instability model is selected, specify the Spray angle constant A (dimensionless). The default value is 0.188.
Nozzle Theory