The validity of the two critical assumptions which simulation of filtration with the data obtained from the compression-permeability cell hinges on is investigated. The first assumption, stating that the sum of the pore liquid pressure and the compressive stress is equal to the applied filtration pressure, requires careful interpretation of the compressive stress. The volume-averaged multiphase equations of change indicate that this is an averaged quantity and, as such, it is dependent not only on the characteristics of a solid phase but also on the porosity (or, solidosity). The second assumption presumes the e?ective stress to be the responsible factor for the alteration of porosity and expresses porosity as a power function of the compressive stress. The multiphase equations of change indicate that while the compressive stress is zero at the singular surface of cake-slurry interface, the drag force takes non-zero values. Consequently, if a functionality for the porosity (or, solidosity) is necessary, porosity should depend on the gradient of compressive stress, but not the compressive stress itself. The lack of scientific basis together with the existing methodological problems, such as, sidewall friction, makes the compression-permeability cell a questionable device in simulation of cake filtration. Conclusions based on compression-permeability cell may be correct qualitatively, however, quantitative conclusions are obviously subject to question.
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