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### Restrictor, Contraction

Figure 75: Geometry of a contraction

The geometry of a contraction is shown in Figure 75. It is described by the following constants (to be specified in that order on the line beneath the *FLUID SECTION, TYPE=RESTRICTOR CONTRACTION card):

- full cross section .
- reduced cross section .
- hydraulic diameter defined by where is the perimeter of the cross section.
- chamfer length .
- chamfer angle .
- 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 contraction 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.

Example files: piperestrictor, restrictor, restrictor-oil.