Continuous surface force, CSF

The VOF approach allows one to model various interfacial phenomena for example, wall adhesion and surface (or interfacial) tension can be modeled rigorously using this approach. Brackbill et al. (1992) developed a continuous surface force (CSF) model to describe interfacial surface tension. CSF model replaces surface force by a smoothly varying volumetric force acting on all the fluid elements in the interface transition region. For two-phase flows (dispersed or secondary phase is denoted by subscript 2), surface force, Fsf can be written (Brackbill et al., 1992) ... 

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. 

CRE Chemical Reaction (or Reactor) Engineering CSF Continuous Surface Force CSS Continuous Surface Stress CSTR Continuous Stirred Tank Reactor model DCS Deferred Correction Source DM Dispersion Model... 

According to the applied Continuum Surface Force (CSF) method we approximate the Dirac Delta function 5 by a continuous regularized one, which is a smooth function in the vicinity of e of the interface ... 

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