Dissolution of an immobile phase during flow in porous media

In this paper we examine the problem of the dissolution of an immobile phas e during flow in porous media with the objective of deriving an evolutionar y transport equation for the volume fraction of the immobile phase. Both th e speed of displacement of the phase interface and the interfacial mass-tra nsfer coefficient are represented in terms of mapping variables that are de termined by the solution of two closure problems. Other problems of this ty pe include the dissolution and phase change of solids and liquids which can occur because of concentration and temperature gradients. The dissolution of solids is of interest to geologists concerned with transport in sediment ary basins, while engineers are often confronted with freezing and melting processes in multiphase systems. The analysis presented in this paper provi des a theoretical framework for the solution of these problems.