In this two part lecture series, which is in an hour in total for both videos, Dr. Matthew Inman, Ph.D. provides an excellent introduction on how to design a heat sink including:

• Forced Convection
• Fin Spacing Optimization
• Optimizing for Fin Geometry
• Consideration for best materials for a heat sink

Dr. Inman covers quite a bit of material and really focuses on the analytical design piece, covering the equations in some detail.  Its a great watch and helpful for engineers who need to brush up on heat sink design.

Thermal Management: Heat Sink Design I

Thermal Management: Heat Sink Design II
https://www.youtube.com/watch?v=m8r0DZRaj5E