Discussion
A steady incompressible laminar flow passes through a 90° tube bend placed on a horizontal surface. In horizontal diametric plane, two pressure taps \(P_{i}\) and \(P_{o}\) are provided across the cross-section at inner and outer walls of the bend, respectively. Which one of the following options is correct?
Answer: A
The correct option is \(P_{o} \gt P_{i}\).
Fluid going round a bend needs a net force towards the centre of curvature to supply its centripetal acceleration. That force comes from a pressure gradient across the section, with pressure rising outward: \(\partial p/\partial r = \rho V^{2}/r\). So the outer wall sees the higher pressure.
This makes \(P_{o} \lt P_{i}\) wrong. The difference grows roughly as \(\rho V^{2}/R\) times the tube width, so it is inversely, not directly, proportional to the bend radius, and it increases with velocity rather than being inversely proportional to it.
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development