This model outputs the flow velocity flowing from
port_a to port_b.
The sensor is ideal, i.e., it does not influence the fluid. If
the parameter tau is non-zero, then the measured
density that is used to convert the mass flow rate into volumetric
flow rate is computed using a first order differential equation.
Setting tau=0 is not recommend. See AixLib.Fluid.Sensors.UsersGuide
for an explanation.
In order to use the flow velocity sensor, the cross sectional
area of the flow channel crossSection must be
specified in m2. For a circular flow
channel (e.g. a round pipe) of diameter diameter, the
cross sectional area can be specified as crossSection =
diameter * diameter / 4 * Modelica.Constants.pi. See
AixLib.Fluid.Sensors.Examples.Velocity
for an example implementation with diameter = 0.1.