Labs / Physics
Pipe Flow
Drag the throat walls to pinch the pipe, then open the flow rate and watch the streamlines race through the narrow gap. Squeezing the pipe forces the fluid to speed up (continuity) — and where it moves fastest, the pressure gauge drops the lowest (Bernoulli).
vwide 2.35 m/svthroat 8.00 m/sPwide 150 kPaPthroat 119 kPa
What to try
- Pinch the throat as tight as it goes. Why does the fluid there move so much faster than at the wide inlet?
- The pressure is lowest exactly where the fluid is fastest. Does that feel backwards to you?
- Turn up the flow rate. Which changes more — the wide-section speed or the throat speed?
- Tilt the pipe uphill. What happens to the pressure once the fluid also has to climb?
- Can you find a setting where the throat pressure falls below the pressure outside the pipe?