Flow due to chirality in suspensions of magnetotactic bacteria

Phenomena due to chirality are observed in suspensions of magnetotactic bacteria. As a particular example that is simple enough for analysis we consider a layer of magnetotactic bacteria suspension with thickness h and width 2d above a solid wall. The torque dipoles of the bacteria are oriented by an oblique magnetic field, leading to torques distributed on the free interface of the layer. As a result a boundary value problem for the 2D Stokes equation is formulated with a jump of the fluid velocity on the free interface and a no-slip condition on the solid wall. It is solved by the known methods of complex analysis where the flow field is defined by two analytical functions. The solution shows fluid motion perpendicular to the plane defined by the normal to the solid wall and the oblique magnetic field. The numerical value of the velocity and its dependence on the angle of the field inclination is in good agreement with the experimental data [1].
1.K.Bente, G.Kitenbergs, D.Krimans, K.Erglis, M.Belovs, D,Faivre, A.Cebers, arXiv 1707.02827 (2017)