Q1: For a given Reynolds number, in a hydraulically smooth pipe, further smoothening __________ the friction factor.

ANS:A - brings about no further reduction of

For a given Reynolds number in a hydraulically smooth pipe, further smoothening does not bring about any further reduction of the friction factor.

Explanation:

1. Hydraulically Smooth Pipe:
   • A hydraulically smooth pipe is one where the roughness height (relative roughness) is very small compared to the pipe diameter. In such pipes, the friction factor fff is primarily influenced by the Reynolds number ReReRe.
2. Friction Factor Behavior:
   • In the laminar flow regime (low Reynolds numbers), the friction factor fff is independent of the pipe roughness and depends only on ReReRe. For laminar flow in a smooth pipe, fff is 64/Re64/Re64/Re.
   • In the transition and turbulent flow regimes (higher Reynolds numbers), the friction factor fff decreases as the Reynolds number increases. For hydraulically smooth pipes in the fully turbulent flow regime, the friction factor fff can be approximated by the Colebrook equation or estimated using empirical correlations.
3. Effect of Further Smoothening:
   • Once a pipe is already hydraulically smooth (with very low relative roughness), further smoothening does not significantly reduce the friction factor fff any further.
4. Conclusion:
   • Therefore, for a given Reynolds number in a hydraulically smooth pipe, further smoothening does not change the friction factor fff. The friction factor fff is determined primarily by the flow regime (Reynolds number) and the pipe's hydraulic smoothness.