Saturday, February 27, 2010

Chapter 2 - Problem 2.F2

This problem illustrates the similarity of two distrinct geometries when the flow cross section area is very small.







Sunday, February 21, 2010

Chapter 2 - Problem 2.E2

Laminar flow trough a slit. Again, we derive a parabolic velocity profile.
We start by establishing the momentum balance:





The specific shear stress profile can be determined by using the following boundary condition:





The following example is based on Problem 2.B1, assuming B = 2R






Chapter 2 - Problem 2.D2

For a descendeing liquid film.

a) The equation that represents the velocity profile is derived as follows. We start by deriving the shear stress profile:


Assuming newtonian fluid:

The following figures show the velocity profile for different inclination angles:














The other way to derive the velocity profile:


Sunday, January 10, 2010

Chapter 9 - Problem 9.E1

Free or natural convection...



Chapter 9 - Problem 9.D1

Again, another typo, the electric resistivity is wrong...



Chapter 9 - Problem 9.C1

We could use this problem as a basis to design lubricants.




Chapter 9 - Problem 9.B1

The heat loss reported in the book is 10 time bigger, I believe this is a typo.





Chapter 9 - Problem 9.A1

A typical heat transfer problem....







Chapter 8 - Problem 8.F2

Molecular diameters!, nice way to measure them!.




Chapter 8 - Problem 8.E2

Thermal conductivity of pure liquids. Beware of the weird energy units, ergs, only physicists and chemists use them.




Chapter 8 - Problem 8.D1

Thermal conductivity of gas mixtures....