  We study the interaction-induced migration of bubbles in shear flow and
observe that bubbles suspended in elastoviscoplastic emulsions organise into
chains aligned in the flow direction, similarly to particles in viscoelastic
fluids. To investigate the driving mechanism, we perform experiments and
simulations on bubble pairs, using suspending fluids with different rheological
properties. First, we notice that, for all fluids, the interaction type depends
on the relative position of the bubbles. If they are aligned in the vorticity
direction, they repel, if not, they attract each other. The simulations show a
similar behavior in Newtonian fluids as in viscoelastic and elastoviscoplastic
fluids, as long as the capillary number is sufficiently large. This shows that
the interaction-related migration of the bubbles is strongly affected by the
bubble deformation. We suggest that the cause of migration is the interaction
between the heterogeneous pressure fields around the deformed bubbles, due to
capillary pressure.
