 Translating surfactant-coated bubble

A spherical inviscid bubble moving slowly through a viscous liquid has a dipolar surfactant perturbation. The associated Marangoni stress reduces the tangential velocity from its clean-bubble value towards zero. In the linear regime, with ${\mathbf{u}}_s=A(I-\mathbf{nn})\mathbf{U}$, the consistent Newtonian fluid stress tensor gives $A=-1/[2(1+2\lambda )]$.