The pressure drop for a relatively low Reynolds number flow in a 600 mm diameter, 30 m long pipeline is 70 kPa. What is the wall shear stress?
- A. 0 Pa
- B. 1400 Pa
- C. 700 Pa
- D. 350 Pa
Answer: D. 350 Pa
Explanation: Wall shear stress $\tau_w = \frac{D}{4} \frac{\Delta P}{L} = \frac{0.6}{4} \times \frac{70000}{30} = 350$ Pa.