Fluid Dynamics MCQ with answer and solution

Concept

Bernoulli's equation is derived for an ideal fluid: non-viscous, incompressible, steady and irrotational flow along a streamline.

Formula

p/(ρg) + V²/(2g) + z = constant

Step-by-step solution

1. Bernoulli's equation is obtained by integrating Euler's equation along a streamline. 2. The assumptions are: ideal (non-viscous) fluid, steady flow, incompressible flow, irrotational flow, flow along a streamline. 3. Check each option: compressible is wrong, viscosity zero is correct, unsteady is wrong, rotational is wrong. 4. Answer is (B).

Explanation

Bernoulli's equation assumes an ideal fluid, which means viscosity is zero, so there is no friction loss. The flow must also be steady, incompressible and irrotational. Only option (B) matches these assumptions.

Why the other options are wrong

A: Bernoulli assumes incompressible flow, not compressible. C: Bernoulli assumes steady flow, not unsteady. D: Bernoulli assumes irrotational flow, not rotational.

Shortcut

Remember the ideal fluid conditions: steady, incompressible, non-viscous, irrotational.

Common mistake

Forgetting that real fluids have viscosity, so a head loss term must be added for real flow.