CBE 30355 - Lecture Notes - Sept. 3, 2024
Announcements
Class notes
Read through pages 26-37 of the notes and view the online narration below. Don't forget to complete the quiz in Canvas!
The main points of the lecture were
Goals:
After this class you should be able to:
- Calculate pressure distributions in fluids at rest.
Reading
- The class notes.
- BS&L chapter 1
Additional Readings:
One of the fluid properties we talked about last Thursday was the coefficient of
thermal expansion. To see an extreme example of what can happen if this property
is ignored, check out the link given
here.
Demonstration:
In class today we demonstrated bubbles - or actually anti-bubbles! An ordinary soap bubble is a thin film of soapy water surrounding a sphere of air, and floating around in the air. An anti-bubble is the exact reverse: a thin film of air surrounding a sphere of water and floating around in water. In order to make the anti-bubble last a bit longer we add a little bit of sugar to increase the density of the water inside the air sheath (so that it counterbalances the lower density of the thin air sheath) and thus is neutrally buoyant. From the density of this sugar solution (about 1.2 wt%) and anti-bubble size (2.9mm radius, 0.1ml volume), the thickness of the air sheath is only about 4µm!
A nice article describing how to make anti-bubbles by Kim and Stone is found here.
A short movie of the anti-bubble is given here.
David.T.Leighton.1@nd.edu