Generalized Equation of Syneresis

Equation of syneresis. Syneresis coefficient. Together with the liquid flux (7.4.1) relative to the skeleton phase, there also exists translational transfer VU determined by the local velocity field U of the entire foam (or of its skeleton phase). In this case, the law of conservation of liquid mass has the form 

The left-hand side of (7.4.4) is the substantial derivative of the volume fraction of liquid in foam. The last term on the right-hand side is important only 

In [246] the hydroconductivity and syneresis coefficients were calculated for the channel version of hydroconductivity of polyhedral foam  

We point out that the accuracy of formula (7.4.3) is two times less than that of formula (7.4.6), since the last formula was derived under the assumption that the motion in the walls of Plateau borders is retarded. 

Boundary conditions. The conventional boundary conditions for Eq. (7.4.4) at the boundary of the foam region prescribe the normal component qn of the volume rate of flow per unit volume. This flow characteristic and the variables 

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