Accounting for the instability of a liquid flow front through a porous medium under conditions of low gravity and in the presence of chemical interactions between the phases.

Safe operation of orbital platforms relies heavily on stability of fluid flows in microgravity, which are strongly affected by capillary forces. The paper considers multiphase fluid seepage through a porous medium. Questions of instability of the interface between liquids are discussed. The effect of capillary instability is shown, which was revealed during the processing of experimental data on the imbibition of a porous structure in microgravity conditions during parabolic flights. A mathematical model is proposed to describe the process of multiple imbibition of a porous medium under conditions of variable gravity. The model takes into account hysteresis, various models of capillary pressure are used during imbibition and drainage. The paper also considers a method for modeling the instability by transforming the constitutive equations. The method allows modeling additional blurring of the imbibition front. The results of modeling based on this method for capillary imbibition of a porous medium under microgravity conditions, as well as for the case when chemical interactions occur between flowing fluids, are considered. • The instability of the phase boundary during seepage is considered. • Flows are studied controlling safe operation of spacecraft fluid supply systems. • A new mathematical model for describing the multiple imbibition is proposed • The seepage with chemical interactions between the phases is considered. [ABSTRACT FROM AUTHOR]