The condition of mechanical equilibrium for a non-spherical interface between phases with a non-diagonal stress tensor

A compact form for the condition of mechanical equilibrium for arbitrary cu rved interfaces has been formulated in the case when the bulk pressures are non-diagonal local tensors. This form of the condition is applicable to a non-spherical interface between fluid or solid phases, without or with arbi trary number of any external fields. The equilibrium condition has been tra nsformed into a set of differential equations for the tangential and transv erse components of the mechanical surface tension and bulk pressure tensors at a dividing surface. One condition simplifies to the usual Laplace equat ion of capillarity for the transverse direction across the interface, while the other conditions relate to the tangential equilibrium state of the flu id. The amendment of the definition of a dividing surface has been given. ( C) 2001 Elsevier Science B.V. All rights reserved.