Continuum-Scale Modeling of Liquid Redistribution in a Stack of Thin Hydrophilic Fibrous Layers

A.H. Tavangarrad, Behzad Mohebbi, S.M. Hassanizadeh, Rodrigo Rosati, Jan Claussen, Bernhard Blümich

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Macroscale three-dimensional modeling of fluid flow in a thin porous layer under unsaturated conditions is a challenging task. One major issue is that such layers do not satisfy the representative elementary volume length-scale requirement. Recently, a new approach, called reduced continua model (RCM), has been developed to describe multiphase fluid flow in a stack of thin porous layers. In that approach, flow equations are formulated in terms of thickness-averaged variables and properties. In this work, we have performed a set of experiments, where a wet 260-μm -thin porous layer was placed on top of a dry layer of the same material. We measured the change of average saturation with time using a single-sided low-field nuclear magnetic resonance device known as NMR-MOUSE. We have employed both RCM and the traditional Richards equation-based models to simulate our experimental results. We found that the traditional unsaturated flow model cannot simulate experimental results satisfactorily. Very close agreement was obtained by including the dynamic capillary term as postulated by Hassanizadeh and Gray in the traditional equations. The reduced continua model was found to be in good agreement with the experimental result without adding dynamic capillarity term. Moreover, the computational effort needed for RCM simulations was one order of magnitude less than that of traditional models.
Original languageEnglish
Pages (from-to)203-219
Number of pages17
JournalTransport in Porous Media
Volume122
Issue number1
DOIs
Publication statusPublished - Mar 2018

Keywords

  • Thin porous media
  • Moisture redistribution
  • Low-field NMR
  • Fibrous layer
  • Dynamic capillary pressure
  • Reduced continua model

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