Which term would describe a uniform velocity across the cross-section?

Which term would describe a uniform velocity across the cross-section?

• A. Parabolic flow profile
• B. Plug flow profile
• C. Laminar flow profile
• D. Stagnant flow profile

Answer: (B)

The concept tested is how velocity is distributed across the cross-section of a flowing fluid. Uniform velocity across the cross-section is called plug flow: every fluid element across the radius moves at the same speed, so there’s no radial velocity gradient and no shear across the section. In real pipe flow under laminar conditions, the velocity profile is typically parabolic, with zero velocity at the wall and a maximum at the center, due to viscous effects and the no-slip condition. The plug-flow idealization imagines strong radial mixing that flattens this profile into a flat, uniform velocity across the cross-section, which is useful for simplifying reactor models and residence-time calculations. The other terms describe different ideas: a parabolic flow profile refers to that curved, center-fast, wall-slow distribution; a laminar flow profile is a general smooth-flow regime that can have various velocity shapes (often parabolic in pipes); stagnant flow implies little to no motion throughout the cross-section.

The concept tested is how velocity is distributed across the cross-section of a flowing fluid. Uniform velocity across the cross-section is called plug flow: every fluid element across the radius moves at the same speed, so there’s no radial velocity gradient and no shear across the section.

In real pipe flow under laminar conditions, the velocity profile is typically parabolic, with zero velocity at the wall and a maximum at the center, due to viscous effects and the no-slip condition. The plug-flow idealization imagines strong radial mixing that flattens this profile into a flat, uniform velocity across the cross-section, which is useful for simplifying reactor models and residence-time calculations.

The other terms describe different ideas: a parabolic flow profile refers to that curved, center-fast, wall-slow distribution; a laminar flow profile is a general smooth-flow regime that can have various velocity shapes (often parabolic in pipes); stagnant flow implies little to no motion throughout the cross-section.