UBC Mathematics Department
http://www.math.ubc.ca/
Here is a demonstration of the flow of a vector field. You may choose a vector field from the pull down menu. In the graphing area, select a rectangular region by clicking and dragging. When you release, you will see how the rectangle moves under the flow. The change in the area of the rectangle is described by the divergence of the vector field while the rotation of the sides is described by the curl.
