Flow at high Reynolds number

(Boundary layer theory)

Re-visit the non–dimensionalized NS equation:

At high Reynolds number, viscous effects are considered negligible in the flow away from a solid surface. In other words, fluid is supposed to be inviscid or .

In such case the equation is simplified to

Neglecting the gravitational effect, one can state that the inertial force is balanced by pressure force. Such flow is termed as potential flow.

Assuming 1-D flow, the equation can be integrated to obtain