sigma_2: cavitation index (Reference downstream pressure P2):
In ratral/wcontrolvalve: Meta Analysis Plunger Valves

View source: R/valve_hydrailic_functions.R

The value for the operating service conditions of a valve. Reference downstream pressure and Adding the cavitation caused by surface roughness, an isolated roughness, an offset in the boundary, or by any device for which it is not possible or convenient to evaluate a pressure differential), the velocity head can be used in adding the DP in the Equation.

1	sigma_2(p1, p2, flow, dn, masl, temp)

`p1`	Gauge Inlet pressure (bar).
`p2`	Gauge outlet pressure (bar).
`flow`	flow in (m³/s).
`dn`	valve diameter (mm).
`masl`	meters above sea level (m).
`temp`	The temperature is in Celsius.