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The Molecular Viscous Force
Gravity and electrostatic force
Ion density
Field strength
Newton’s law, the sum of these forces is equal to the mass times its acceleration:
external force density

The Molecular Viscous Force
Change in velocity
Navier-stoke eq.

The Molecular Viscous Force
All real Fluids are subject to internal friction, which is called viscosity.
To gain an understanding of this, we consider a very simple case,
with a flow confined between two solid plates:
The lower plate is stationary, and the upper plate is moving in the x-direction with speed V0.
The plates are separated by a distance Z
v0

A force is required to keep the upper plate in motion. Experiments show that this force is :
? proportional to the area A of the plates
? proportional to the velocity v0
? inversely proportional to the distance Z between the plates.

The constant of proportionality η is called the dynamic viscosity coefficient.
For a steady state (unaccelerated motion) each layer of fluid of depth z must exert the same force on the fluid below, and the fluid below must exert a contrary force of the same magnitude.
The Molecular Viscous Force

참고 자료

http://www.millersville.edu/~jdooley/macro/derive/viscous/visplat/visplat.htm
http://muweb.millersville.edu/~jdooley/macro/macrohyp/viscous/viscou.htm