Instability of a thin film of chemotactic active suspension

In this paper, we analyse the instability of a thin-film suspension micro-swimmers subjected to an attractant gradient. The imposed gradient introduces preferential swimming direction for swimmers, resulting in anisotropic orientation field. By modelling swimmers as force dipoles, study by Kasyap & Koch ( Phys. Rev. Lett. , vol. 108, issue 3, 2012, 038101, J. Fluid Mech. 741, 2014, pp. 619–657) found arising from coupling between active stress associated with field and perturbations swimmer density work begin presenting stability analysis that calculates modification presence interface. We then detail new mode arises solely deformation interface mediated suspension. hydrodynamic instabilities system are observed be sensitive relative Furthermore, show two modes involving jump interfacial viscous stresses normal differences within allows manifest chemotactic pullers, previously thought unconditionally stable. use long-wave theory write down set nonlinear equations governing film evolution. numerical solution using aids explaining mechanism addition validating predictions linear theory.