### Restrictor, User

Properties: adiabatic, not isentropic, directional, inlet based restrictor if and outlet based restrictor if .

A user-defined restrictor is described by the following constants (to be specified in that order on the line beneath the *FLUID SECTION, TYPE=RESTRICTOR USER card):

• upstream cross section .
• downstream cross section .
• hydraulic diameter defined by where is the area of the smallest cross section and is the perimeter of the smallest cross section.
• loss coefficient .
• oil mass flow in the restrictor (only if the OIL parameter is used to define the kind of oil in the *FLUID SECTION card)
• not used (internally: oil material number)

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.

Example files: restrictor, restrictor-oil.