Question

Reynold’s number is the ratio of ____________

(a) Inertia force to viscous force

(b) Viscous force to inertia force

(c) Inertia force to gravity force

(d) Pressure force to inertia force

The question was asked in unit test.

My question is based upon Infinitesimal Fluid Element topic in division Aerodynamics – Fundamental Principles and Equations of Aerodynamics

Answer 1

Correct answer is (a) Inertia force to viscous force

To elaborate: Reynold’s number is given by Re = VL ρ / μ, which signifies the inertia to viscous force occurring in a flow.  ρ / μ is called as kinematic viscosity of the fluid. Larger Reynold’s number, greater will be the inertial effects.