Credit: K. Drescher, R. E. Goldstein, N. Michel, M. Polin, and I. Tuval, University of Cambridge
Flow field around a swimming Volvox carteri. The spherical Volvox, located at the center of the image, is swimming towards the top. Streamlines appear as red curves, and the color map corresponds to the fluid velocity magnitude. As demonstrated by Drescher and co-workers, this flow can be accurately described as the superposition of a Stokeslet and source doublet, with a small stresslet contribution .