#### Capillary interactions between nearby interfacial objects Europhys. Lett. 102, 38001 (2013) PDF

##### by He, Nguyen and Mandre

Fluid Mechanics Capillary Cheerios Effect**Abstract:**

We develop a general method to study the capillary interactions between objects of arbitrary shape which float close to each other on an interface, a regime in which multipole expansion is not useful. The force is represented as a power series in the small distance between the objects, of which the leading order is finite. For objects with size a much larger than the capillary length *l _{c}*, the force scales as

*(a/l*and the prefactor depends on the mean radius of curvature

_{c})^{1/2}*R*at the closest points. After contact the objects roll and/or slide with respect to each other to locally maximize

*R*and therefore the force. For smaller objects (

*a < < l*), the force scales as

_{c}*(a/l*, and the prefactor depends only weakly on the shape and relative orientation of the objects.

_{c})^{-1}/log(a/l_{c})^{2}