Unidirectional flows in 2D Cartesian coordinates (also known as channel flows) are defined as systems with only one velocity component, say vx

Unidirectional flows in 2D Cartesian coordinates (also known as channel flows) are defined as systems with only one velocity component, say vx. How does the continuity simplify for such problems? Verify that vx can be a function of y but not a function of x. How does the Navier–Stokes equation simplify for such problems? How does it compare with the equations derived from a basic shell balance in Section 2.5.3? 6. Unidirectional flows can also be posed as vx as a function of y and z. A flow in a square duct (away from the entrance region) is an example. How does the Navier–Stokes equation simplify for such problems?