At low Reynold’s number, the power (P) required for agitating a fluid in a stirred tank becomes independent of inertial forces. In this limit, indicate which of the following relations is satisfied: Po = ρ/ρN3 D5: Power number Re = ρ N D2/μ: Reynold’s number N is the impeller rotational speed, and D is the impeller diameter ?

Question

Accepted Answer

Po ∝ Re0.0. At low Reynolds numbers (laminar flow), the power number (Po) becomes constant and does not depend on the Reynolds number (Re). This means Po is proportional to Re raised to the power of 0.