StreamPlot

StreamPlot[{vx, vy}, {x, xmin, xmax}, {y, ymin, ymax}] generates a stream plot showing flow lines of a vector field.

Examples

Plot stream lines:

(* Rotational flow *)
StreamPlot[{-y, x}, {x, -2, 2}, {y, -2, 2}]

(* Source/sink flow *)
StreamPlot[{x, y}, {x, -2, 2}, {y, -2, 2},
  StreamColorFunction -> "Rainbow"
]

Please visit the official Wolfram Language Reference for more details.