A control volume round an aerofoil
A rectangle drawn in the fluid around a lifting section. The arrows on the right-hand face show the downward velocity of the air leaving it, drawn to scale. Adding the momentum carried through all four faces to the pressure acting on them gives the force on whatever is inside, without the calculation ever going near the surface.
7 essays call
control-volume. The drawing above is what it returns with no arguments at all; every
call below passes it something, because a placement that passes nothing draws whichever member
of the family the generator happens to default to rather than the one its essay argues about.
It is also the blast radius. Changing control-volume changes every figure listed here
at once, and on this site it may change what they assert as well as what they show —
which is what has to be rebuilt and looked at before the change is believed.
Where it is called
What each of these essays asks for instead of the defaults is on the regime index, which reads the parameters back out of the finished figures rather than out of the placements.
- Air must be pushed down, and the usual sum is wrong What is taught wrongly
- A loss with no viscosity in it Fluids at work
- What averaging costs Transition and turbulence
- Work out of a change of swirl Fluids at work
- Where the reaction to a wing's lift is Ideal flow
- Weighing what is missing What is taught wrongly
- The drag a wake keeps however it rolls up What is taught wrongly