CBE 30356 - Lecture Notes - March 2, 2023
Announcements
- Remember that the mid-term exam will be one week from today!
Class notes
Read through pages 198-213 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
- Forced convection heat transfer correlations for external flow
- Origin of natural or free convection
- Scaling of natural convection for a heated plate
Goals:
After this class you should be able to:
- Know how to calculate the heat transfer coefficient for forced convection.
- Know how to calculate the heat transfer coefficient for free convection.
- Understand how velocities and temperature gradients scale in free convection flows.
Reading
- The class notes.
- BS&L, 14.4, 14.6, 11.4-5
Problem of the Day:
In class today we will solve the equations for laminar free convection past a vertical plate numerically. The notes for converting the PDEs to ODEs is given here and the short program for solving the system of equations is miss8.m. This is an illustration of how a very difficult non-linear problem can be solved easily if it admits a self-similar solution!
Demonstration:
In class today we demonstrated the squeeze flow of a concentrated suspension. There are a number of aspects to this: the difference between flow average and volume average concentration (the difference piles up at the meniscus), the viscous fingering instability which occurs when a more viscous fluid is displaced by a less viscous one (think trapped oil in tertiary oil recovery), and the scaling associated with shear-induced particle migration. The scaling analysis which allows us to predict the radius at which the effect is observable is given here.
David.T.Leighton.1@nd.edu