Mass transport in a partially covered fluid-filled cavity

A method of computing the concentration field of dissolved material inside an etch-hole is presented. With a given velocity field, approximate convect ion-diffusion equations are formulated using a number of assumptions, and a nalytical descriptions for the concentration in different parts of the doma in are obtained. By coupling these descriptions the concentration field can be computed. The assumptions and the results are validated by comparison w ith solutions based on a finite-volume method. Results of the boundary-laye r method are given for two characteristic etch-hole geometries. The describ ed boundary-layer method is efficient in terms of computational time and me mory, because it does not require the construction of a computational grid in the interior of the domain. This advantage will be exploited in a future paper where the method will be used to simulate wet-chemical etching. (C) 2000 Elsevier Science Ltd. All rights reserved.