Which type of gas flow occurs when the flow velocity exceeds the critical velocity?

Which type of gas flow occurs when the flow velocity exceeds the critical velocity?

• A. Laminar flow
• B. Orifice flow
• C. Turbulent flow
• D. Stenotic flow

Answer: (C)

When flow velocity passes a certain threshold, inertial forces overcome the damping effect of viscosity, so the smooth, parallel layers of fluid can’t stay separate. This transition is set by the Reynolds number; once it exceeds a critical value, the flow becomes chaotic and irregular. That chaotic state is turbulent flow, with eddies and fluctuations of various sizes and more energy loss due to mixing. So, exceeding the critical velocity leads to turbulent flow. Laminar flow is the smooth, orderly state that occurs at lower Reynolds numbers. Orifice flow describes flow through a restriction and isn’t defined by a velocity threshold. Stenotic flow refers to flow altered by a narrowed passage and, again, isn’t about exceeding a specific critical velocity.

When flow velocity passes a certain threshold, inertial forces overcome the damping effect of viscosity, so the smooth, parallel layers of fluid can’t stay separate. This transition is set by the Reynolds number; once it exceeds a critical value, the flow becomes chaotic and irregular. That chaotic state is turbulent flow, with eddies and fluctuations of various sizes and more energy loss due to mixing. So, exceeding the critical velocity leads to turbulent flow.

Laminar flow is the smooth, orderly state that occurs at lower Reynolds numbers. Orifice flow describes flow through a restriction and isn’t defined by a velocity threshold. Stenotic flow refers to flow altered by a narrowed passage and, again, isn’t about exceeding a specific critical velocity.