Experimenting with photographing moving things at different shutter speeds, the only convenient thing in front of my armchair was the pedestal fan:  this swoosh effect came from the effect of the fan oscillating towards me when I had a long shutter speed of one second, causing all that overexposure.  But I liked the swoosh from the centre of the fan upwards!
Technical details: Shutter Priority, shutter speed one second
F8, ISO 800, AF 1 area, white balance - auto