Anyone else having problems interpreting K & W's chapter 12 on cooling?

I confess to only having available (downloaded) chapters  on inlets & cooling, but their use of terms is a bit hair-pulling for me. For instance, VsubB is defined on the 1st page of the chapter as 'velocity of the air ahead of the block' & diagrammed that way in fig 12-1, then it's apparently diagrammed as the velocity *leaving* the cooling block in fig 12-6. And quite a few of the terms don't seem to be defined at all (this may be due to my failure to take a physics course in college, & the 30+ year interval since my one semester of Calculus...).

If there's a 'K&W for Dummies' book, please recommend a source...

Charlie