Stokes flow is also known as creeping flow, with inertial forces small relative to viscous forces. Which term describes this flow?

Stokes flow is also known as creeping flow, with inertial forces small relative to viscous forces. Which term describes this flow?

• A. Turbulent flow
• B. Creeping flow
• C. Laminar flow
• D. Dilatant flow

Answer: (B)

When inertial effects are negligible compared with viscous effects, the flow is governed by the Stokes equations, describing a linear, highly damped response. This regime is called creeping flow because the motion proceeds so slowly (or the fluid is so viscous) that inertia cannot sustain forward momentum and the flow “creeps” around obstacles. It corresponds to a very low Reynolds number (Re ≪ 1), and while the flow is laminar, creeping flow is the specific term for this extreme low-inertia limit. Turbulent flow requires significant inertia and chaotic fluctuations, so it does not describe this regime. Dilatant flow refers to a non-Newtonian shear-thickening behavior and is not the situation described by Stokes flow.

When inertial effects are negligible compared with viscous effects, the flow is governed by the Stokes equations, describing a linear, highly damped response. This regime is called creeping flow because the motion proceeds so slowly (or the fluid is so viscous) that inertia cannot sustain forward momentum and the flow “creeps” around obstacles. It corresponds to a very low Reynolds number (Re ≪ 1), and while the flow is laminar, creeping flow is the specific term for this extreme low-inertia limit. Turbulent flow requires significant inertia and chaotic fluctuations, so it does not describe this regime. Dilatant flow refers to a non-Newtonian shear-thickening behavior and is not the situation described by Stokes flow.