fluid lab

Experiment B: Shape of a Falling Liquid Jet

Materials:

· 100 ml graduated cylinder

· Stopwatch application

· Two rulers (one long, one short)

· Measuring tape

· Stainless steel funnel

Procedure:

1. Press funnel underneath faucet so that they touch.

2. Have another group member ready with a stopwatch.

3. Turn on the faucet and slowly adjust until a laminar flow is produced. The water should be transparent and smooth.

4. Have the third group member slip the graduated cylinder below the stream and start the stopwatch.

5. When the graduated cylinder has been filled to approximately the 80 ml mark, stop the stopwatch, and record the data.

6. Remove the graduated cylinder.

7. At a distance of L = 5 cm from the bottom of the funnel, use the ruler to estimate the stream diameter, D.

8. At L = 10, 15, 20 and 25 cm, estimate the stream diameter.

9. Repeat Steps 3-8 three times to get average values of all parameters (you might want to switch jobs, as holding the funnel can become tiresome…)

10. Place materials to the right of the sink.

Report Results:

· Use a control volume analysis to estimate the fluid velocity V at each measured L.

· Using the V (L = 5 cm), predict V at each of the other values of L.

· Using Excel or MATLAB, plot D (cm) vs L (cm).

· On a second graph, plot two clearly-labelled curves: a) the measured (based on D) values of V (m/s) vs L (cm), and b) V vs L based on your predictions from a single velocity measurement - V(L = 5 cm).

Report Discussion:

· List and explain your assumptions made to derive the equations used in your analysis. Comment on their validity.

· Comment on sources of error in this experiment.

· What happens to the liquid jet diameter as you move downward along the jet? Why does this occur?

· Why might the fluid velocity change along the jet?