ITL Researchers Consider Diffuse-Interface Model for
Fluid-Fluid Systems
January 1997
NISTIR 5887, A Diffuse-Interface Description of Fluid Systems, describes
a diffuse-interface model for fluid-fluid systems. In classical models,
an interface between two fluids is treated as infinitely thin, or sharp,
and is endowed with properties such as surface tension. Diffuse-interface
theories replace this sharp interface with continuous variations of an
order parameter such as density in a way consistent with microscopic theories
of the interface. ITL researchers related the diffuse-interface models
by deriving asymptotically the governing equations and the associated boundary
conditions used in the sharp-interface formulation. The diffuse-interface
approach is illustrated by modeling internal gravity waves. Results reveal
a singularity in the diffuse-interface model in the limit of incompressible
perturbations.
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