Details

The stream functions for source, vortex, and doublet elementary flows are , , and , respectively, where is a measure of the strength of the flows.

The velocities are obtained from and . Next and are replaced by and to obtain the velocity at with strength as follows.

The source flow , from the point) or sink flow (, to the point):

Vortex flow , clockwise rotating) or , counterclockwise rotating):

Doublet flow , left through the point) or , right through the point):

Uniform flow:

This uniform flow is equivalent to the flow with velocity in the direction .

The velocity field stream lines are plotted by using superposition of the above velocities with strength located at the points .

It is interesting to compare this Demonstration with the applet given in the related links. The results are similar but the vortex positive rotation here is clockwise, while there it is counterclockwise.

See the applet on the superposition of elementary flows.