Models for describing multiphase flow and transport of contaminants

The presence of nonaqueous-phase liquids (NAPLs) in a wide range of contaminated sites has created the need for a thorough understanding of the relevant characteristics and processes. Over the years, many models have been developed to improve this understanding the help design effective remedial strategies. This chapter is an introduction to the existing and ever-expanding choice of models that deal with multiphase flow problems. Most models currently available are limited in the type of remediation technologies that may be simulated; hence, the discussion is categorized according to the type of technology. An overview familiarizes the reader with the various chemical and physical phenomena that are pertinent to these models. Almost all modeling applications still require some simplifying assumptions, which must be carefully selected and evaluated. It is crucial to clearly understand the effect of making certain assumptions on the modeling outcome. Two case studies of model application to real-world contaminated sites are presented to highlight the importance of adequate selection of models and key simplifying assumptions.