  Swimming in circles occurs in a variety of situations at low Reynolds number.
Here we propose a simple model for a swimmer that undergoes circular motion,
generalising the model of a linear swimmer proposed by Najafi and Golestanian
(Phys. Rev. E 69, 062901 (2004)). Our model consists of three solid spheres
arranged in a triangular configuration, joined by two links of time-dependent
length. For small strokes, we discuss the motion of the swimmer as a function
of the separation angle between its links. We find that swimmers describe
either clockwise or anticlockwise circular motion depending on the tilting
angle in a non-trivial manner. The symmetry of the swimmer leads to a
quadrupolar decay of the far flow field. We discuss the potential extensions
and experimental realisation of our model.
