a steady uniform flow

an unsteady uniform flow

a steady non-uniform flow

an unsteady non-uniform flow

a steady uniform flow

an unsteady uniform flow

a steady non-uniform flow

an unsteady non-uniform flow

$$\nabla .\overrightarrow V = 0$$

$$\nabla \times \overrightarrow V = 0$$

$$\left( {\overrightarrow V .\nabla } \right)\overrightarrow V = 0$$

$${{\partial \overrightarrow V } \over {\partial t}} + \left( {\overrightarrow V .\nabla } \right)\overrightarrow V = 0$$

are parallel to each other

are perpendicular to each other

intersect at an acute angle

are identical