Multivariate calculus: intuition behind divergence.
I am trying to understand intuitively why del dot f gives the divergence. I'm using
http://betterexplained.com/articles/divergence/
and I am told to "Imagine a cube at the point we want to measure, with sides of length dx, dy and dz. To get the net flux, we see how much the X component of flux changes in the X direction, add that to the Y component’s change in the Y direction, and the Z component’s change in the Z direction." I don't see how the x component's change in the x direction gives flux... isn't flux flow perpendicular to the surface?

Question

Multivariate calculus: intuition behind divergence.
I am trying to understand intuitively why del dot f gives the divergence. I'm using 
http://betterexplained.com/articles/divergence/
and I am told to "Imagine a cube at the point we want to measure, with sides of length dx, dy and dz. To get the net flux, we see how much the X component of flux changes in the X direction, add that to the Y component’s change in the Y direction, and the Z component’s change in the Z direction." I don't see how the x component's change in the x direction gives flux... isn't flux flow perpendicular to the surface?

inkyvoyd · Answer

nevermind, think I"m getting it using http://www2.sjs.org/raulston/mvc.10/Topic.6.Lab.4.htm

kainui · Answer

change in the x direction IS perpendicular to the yz plane which is the surface.

inkyvoyd · Answer

... herp a doo

irishboy123 · Answer

yeah

that sounds like bullsh1t

divergence measures the lack of change/ conservatism.