shedding is a physical phenomenon occurring in nature.
As flow passes a bluff body in the flow stream, vortices are
alternately shed on either side of the bluff body. This
effect can be observed in the fluttering of a flag. The
flag pole acts as a bluff body to the wind. The flag
waves in response to the vortices shed as the wind passes the
flag pole. According to well proven physical laws, the
frequency at which vortices are alternately shed is directly
proportional to the flow velocity.
vortices create low and high pressure zones behind the bluff
body. The V-Bar uses dual semiconductor strain gauges to
detect the pressure exerted by the vortices on the sensing
wing. The strain gauges generate an electric frequency
signal, which is proportional to the local velocity at the
The "Smart", microprocessor-based electronics
calculates the local velocity, using a linear relationship
developed during calibration, between the sensor input
frequency and velocity. The electronics then
translates the local velocity into an average flow velocity
and then into a flow rate, based on user-selected engineering
units. The 8-character, 2-line, local display alternates
between flow rate and totalized flow. A 4-20 mA current
output and a frequency/pulse output are standard.