Pipe, Diaphragm

Figure 115: Diaphragm

A diaphragm (Figure 115) is characterized by head losses $ \Delta_1^2 F$ of the form:

$\displaystyle \Delta_1^2 F = \zeta \frac{\dot{m}^2}{2 g \rho^2 A^2 },$ (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 diaphragm 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 DIAPHRAGM card:

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.