Use the mouse to draw a curve. Pressing and releasing the mouse button sets a point for a polygonal line. Dragging the mouse enters a continuous curve. If you do not see a drawing panel above and only see two horizontal lines, then your browser may not be Java enabled. Click here for a version that uses an adjustable rectangular grid.
Curves collapse to ellipses instead of circles.
Click here for a version that flows two curves simultaneously. This article can be found in Topology Vol. The disk flow algorithm curve shortens a curve on a surface by covering it with a sequence of convex disks and replacing the portion of the curve inside of each disk with the unique geodesic segment that preserves the end points. In this application, the surface is a plane and so the geodesic segments are all line segments. The sequence of disks used is a grid of squares.