Snapshots of Prandtls starting vortex formed behind a plate impulsively started from rest are shown below. The flow was visualized with aluminium flakes sprinkled on the water surface. These flakes provide a strong signal that can be used for Particle Image Velocimetry analysis. Prandtls movie was unpacked and successive frames were used to produce velocity field snapshots. The associated streamline pattern and vorticity fields are shown below. While the vortex is small in relation to the plate width the growth of the spiral should be self-similar, of a form predicted by Pullin[1]

               Figure 1: Streamline field and vorticity field

                    Figure 2 Streamline field and vorticity field at later time