Pipe, Entrance

**Figure:** Entrance
$\begin{figure}\epsfig{file=Entrance.eps,width=8cm}\end{figure}$

A entrance (Figure ) is characterized by head losses \Delta_1^2 F of the form:

\Delta_1^2 F = \zeta \frac{\dot{m}^2}{2 g \rho^2 A^2 },

(156)

where \zeta is a head loss coefficient depending on the ratio A_0/A, \dot{m} is the mass flow, g is the gravity acceleration and \rho is the liquid density. A_0 and A are the cross section of the entrance and of the pipe, respectively. Values for \zeta can be found in file “liquidpipe.f”.

The following constants have to be specified on the line beneath the *FLUID SECTION, TYPE=PIPE ENTRANCE card:

A
A_0 \;\;\;(\le A)

The gravity acceleration must be specified by a gravity type *DLOAD card defined for the elements at stake. The material characteristic \rho can be defined by a *DENSITY card.

Example files: pipe, piperestrictor.