ME 111 · Fluid Dynamics
Fluid Dynamics Experiment: Water Flow from Jar to Straw
A water-flow experiment using a sealed jar and glass straw. I used measured volume and drain time to calculate flow rate, exit velocity, and Reynolds number, then compared the system with an energy-balance model.
ME 111 · Fluid Dynamics · April 29, 2025
Analyzing Head Loss, Velocity, and Flow Regime
Experiment overview
The setup used a sealed 500 mL jar draining through a glass straw. I investigated how measured flow compared with calculations for a gravity-driven system.
Question
What flow rate and exit velocity does the setup produce, and what does the Reynolds number indicate about the flow regime?
Measurements and calculations
I measured drained volume and elapsed time for water at 20 °C. The straw diameter was 0.00749 m and the water-surface-to-exit drop was 0.3642 m. I used the resulting flow rate with Bernoulli’s equation, loss terms, and a Reynolds number calculation.
Results and interpretation
The recorded flow rate was 1.67 × 10⁻⁵ m³/s, with an exit velocity of 0.378 m/s. The calculated Reynolds number was 2828, which I classified as transitional. The reported head loss was 0.0182 m. The measured flow and calculated losses gave me a way to compare the physical setup with the energy-balance model.
Fluid DynamicsHead LossBernoulliReynolds NumberExperimental