Continuum surface stress, CSS

The second fairly modern group of methods introduces (of numerical reasons) a 3D continuous surface force (CSF) or a 3D continuum surface stress (CSS) acting locally within the whole transition region constituting a meso-scale interface. Notice that since we are primarily interested in the interfacial forces, the latter group of techniques were used approximating the surface effects without actually reconstructing the interface. 

For this reason the surface tension force can be interpreted as a correction to the momentum stress tensor, i.e., it represents a continuum surface stress (CSS) tensor. 

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