Ventury effect is present in most important systems within the maritime industry which includes dredgers, pumps and waste disposal. But how does it work and what dynamics and laws govern its operation.

1. Venturi Effect
Its Role in Maritime
Ops.

2. What is it?
 Reduction in fluid pressure that results when
fluid flows through a constricted section of
pipe.
 Velocity of fluid increases as cross-sectional
area decreases as static pressure
correspondingly decreasing; Jet effect.
 Named after Giovanni Battista Venturi
(1746–1822 ) Italian physicist.

3. Workings
 “Fluid velocity must increase
as it passes through a
constriction to satisfy
principles of continuity while
its pressure must decrease to
satisfy the principle of
conservation of mechanical
energy; Gain in kinetic
energy in a fluid may accrue
due to its increased velocity
though constriction is
regated by a drop in
pressure.” Laws of Fluid
Dynamics.
 When a fluid such as water
flows through a tube that
narrows to a smaller diameter
and partial restrictions cause
a higher pressure at the inlet
than the narrow end.
Pressure difference causes
the fluid to accelerate
towards the low pressure
narrow section in which it
maintains a higher speed.

4. Choked Flow
 Limiting case of Venturi
effect: When fluid reaches
state of choked flow where
the fluid velocity approaches
the local speed of sound. In
choked flow, the mass flow
rate will not increase with a
further decrease in the
downstream pressure
environment. Mass flow rate
for a compressible fluid can
increase with increased
upstream pressure which will
increase density of fluid
through constriction; velocity
remains constant.

5. Uses and Presence
 Cargo eductor/ejector on oil
product and chemical
tankers.
 Flue gas scrubbers.
 Ventilators
 Emptying bilge water from
moving boats via hull waste
gate; air pressure inside
being greater than water.
 Dredging

6. Summary
 Reduction in fluid pressure that results when a fluid
flows through constricted section of a pipe.