Mechanical Engineering - Hydraulics and Fluid Mechanics - Discussion


The Bernoulli's equation is based on the assumption that

[A]. there is no loss of energy of the liquid flowing
[B]. the velocity of flow is uniform across any cross-section of the pipe
[C]. no force except gravity acts on the fluid
[D]. all of the above

Answer: Option D


No answer description available for this question.

Fahad said: (Oct 20, 2015)  
Apart from gravity force pressure force is also taken into consideration as per the Euler's criteria.

So I don't agree with option C.

Venkat said: (Jun 5, 2016)  
I think option c is wrong.

Akashdeep Singh said: (Feb 23, 2017)  
B is incorrect as according to Bernoulli, the sum of pressure, potential and kinetic heads are same throughout the flow. So, with the change in velocity pressure may vary though satisfying Bernoulli.

Rajiv said: (Jun 6, 2017)  
I think about option A- as Bernoulli equation is basically conservation of mechanical energy. So net mec energy is conserved.

Option B- is incorrect because the equation is applicable in the case of venturi meter where velocity is not uniform. So the assumption of uniform velocity is contradictory with venturi meter. Option C is standard wrong.

S. Ata said: (Jan 14, 2018)  
All assumptions are taken when deriving the Bernoulli's equation:-

i. Fluid is ideal and incompressible.
ii. flow is steady
iii. Flow is along the streamline ie. One dimensional.
iv. The velocity is uniform over the section and is equal to mean velocity.
v. The only forces acting on the fluid are the gravity forces and pressure forces.

So Given answer Option D is correct.

Mahi said: (Jun 25, 2019)  
A is correct.

Works on energy conservation.

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