ANS:B - Hagen and Poiseuille

The experimental study of laminar fluid flow through a circular tube was conducted by Hagen and Poiseuille.

Explanation:

1. Hagen and Poiseuille:
   • In the mid-19th century, Gotthilf Hagen and Jean Léonard Marie Poiseuille independently conducted experimental investigations on fluid flow through pipes.
   • They studied laminar flow (low Reynolds number flow) through cylindrical pipes and derived the empirical relationship that describes the flow rate (volumetric flow) QQQ through a pipe: Q=πr48μL(P1−P2)Q = \frac{\pi r^4}{8 \mu L} (P_1 - P_2)Q=8μLπr4​(P1​−P2​) where:
     • rrr is the radius of the pipe,
     • μ\muμ is the dynamic viscosity of the fluid,
     • LLL is the length of the pipe,
     • P1P_1P1​ and P2P_2P2​ are the pressures at two points along the pipe.
2. Contributions:
   • Hagen and Poiseuille's experiments and subsequent theoretical work provided foundational insights into fluid dynamics, particularly laminar flow characteristics and the relationship between pressure drop and flow rate.
   • They demonstrated that the flow rate in laminar flow is directly proportional to the pressure gradient and the fourth power of the radius of the pipe.
3. Other Contributors:
   • Reynolds: Osborne Reynolds later extended the understanding of fluid flow by introducing the concept of Reynolds number to distinguish between laminar and turbulent flow regimes.
   • Pascal: Blaise Pascal contributed to fluid mechanics through his studies on fluid pressure, but he did not specifically conduct experiments on laminar flow in pipes.
   • Blake-Plummer: This name does not specifically relate to the experimental study of laminar flow through circular tubes.

Conclusion: