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Bernoulli Equation

For fluid energy, the law of conservation of energy is represented by the Bernoulli equation(for ideal fluid only):



Z1= elevation, ft (m), at any point 1 of flowing fluid above an arbitrary datum

Z2= elevation, ft (m), at downstream point in fluid above same datum

p1= pressure at 1, lb/ft2 (kPa)

p2= pressure at 2, lb/ft2 (kPa)

w= specific weight of fluid, lb/ft3 (kg/m3)

V1= velocity of fluid at 1, ft/s (m/s)

V2= velocity of fluid at 2, ft/s (m/s)

g= acceleration due to gravity, 32.2 ft /s2 (9.81 m/s2)


The left side of the equation sums the total energy per unit weight of fluid at 1, and the right side, the total energy per unit weight at 2. The equation for real fluid consist of a value due to head loss due to friction.

This is given below


The term P/W is called pressure head and V*V/2g is called velocity head.

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Kanwarjot Singh

Kanwarjot Singh is the founder of Civil Engineering Portal, a leading civil engineering website which has been awarded as the best online publication by CIDC. He did his BE civil from Thapar University, Patiala and has been working on this website with his team of Civil Engineers.

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One comment on "Bernoulli Equation"

Suman Ganguly says:

Good Work.
Keep it up!

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