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### Restrictor, Wall Orifice

Figure 77: Geometry of a wall orifice

The geometry of an wall orifice is shown in Figure 77. It is described by the following constants (to be specified in that order on the line beneath the *FLUID SECTION, TYPE=RESTRICTOR WALL ORIFICE card):

- reduced cross section .
- hydraulic diameter defined by where is the perimeter of the cross section.
- length L
- oil mass flow in the restrictor (only if the OIL parameter is used to define the kind of oil in the *FLUID SECTION card)

The loss coefficient for a wall orifice is taken from [28].

By specifying the parameter LIQUID on the *FLUID SECTION card the loss is calculated for liquids. In the absence of this parameter, compressible losses are calculated.