Which term describes flow with random variations in pressure?

• A. Laminar
• B. Turbulent
• C. Plug
• D. Stratified

Answer: (B)

Flow with random variations in pressure is turbulent flow. In turbulence, the fluid moves chaotically, with eddies and swirls that cause pressure and velocity to fluctuate unpredictably over time and space. This chaotic motion leads to rapid mixing and a broad range of eddy sizes, often associated with higher energy dissipation and a higher Reynolds number.

Laminar flow, by contrast, is smooth and orderly, with fluid layers sliding past each other in parallel; pressure and velocity stay steady and predictable. Plug flow describes a nearly uniform velocity across the channel cross-section, which can be seen in certain laminar regimes or specialized reactors, but it does not inherently involve random pressure fluctuations. Stratified flow involves distinct layers of fluid with minimal mixing, driven by density differences, and also lacks the chaotic fluctuations seen in turbulence.

So the term describing flow with random variations in pressure is turbulent, because its defining feature is those chaotic, fluctuating motion and pressure signals.