Question

Which of the following sentences are true for Bernoulli's equation? 1 Bernoulli's principle is applicable to ideal incompressible fluid. 2. The gravity force and pressure forces are only considered in Bernoulli's principle 3. The flow of fluid is rotational for Bernoulli's principle 4. The heat transfer into or out of fluid should be zero to apply Bernoulli's principle

		(1), (2) and (3)
		(1), (3) and (4)
		(1), (2) and (4)
		(1), (2), (3) and (4)

Answer 1

Answer 1,2 and 4

Assumptions of Bernoulli's principle are:

• the flow must be steady, i.e. the flow parameters (velocity, density, etc...) at any point cannot change with time
• the flow must be incompressible – even though pressure varies, the density must remain constant along a streamline
• friction by viscous forces must be negligible
• flow must be Non turbulent i.e.,flow must be irrotational

Bernoulli's principle can be derived from the principle of conservation of energy. This states that, in a steady flow, the sum of all forms of energy in a fluid along a streamline is the same at all points on that streamline. This requires that the sum of kinetic energy, potential energy and internal energy remains constant.