Bernoulli’s equation is derived based on the following assumptions

i. There is no loss of energy in a liquid flow and flow is uniform

ii. The flow is rotational

iii. Except gravity and pressure forces, no external force acts on liquid flow

iv. The flow is viscous, incompressible flow

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  1. (i) & (iii)
  2. (i), (ii) & (iv)
  3. (ii) & (iii)
  4. (i), (iii) & (iv)

Answer (Detailed Solution Below)

Option 1 : (i) & (iii)
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Detailed Solution

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Explanation:

Bernoulli’s equation:

\(\frac{P}{\rho g} + \frac{{{v^2}}}{{2g}} + Z = Constant\)

  • It can be derived from the principle of conservation of energy.
  • It 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.
  • It represented in head form (the total energy per unit weight).

Following assumption are made in deriving the Bernoulli’s equation:

  1. Fluid is inviscid i.e. zero viscosity.
  2. Flow is in steady-state.
  3. Flow is incompressible.
  4. Flow is irrotational.
  5. Flow is along the streamline.
  6. Only gravity and pressure force acting on the liquid, no other external force.

Important Points

Even if the flow is rotational, we can still apply the Bernoulli’s equation but only along a streamline.

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