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Presentation
Should tortuosity still be used in upscaling?
AGU (2009)
  • Francisco J. Valdes-Parada
  • Mark L. Porter, Oregon State University
  • Brian D. Wood, Oregon State University
Abstract

The concept of tortuosity is an integral part of models that describe trans- port in multiscale systems. Traditionally, tortuosity is de ned as the ratio of an e ective path length to the shortest path length in a representative sample of the porous medium microstructure. While the latter can be unambiguously speci ed, the same is not true for the e ective path length, since it changes from one type of transport to another. Consequently, it is possible to have di erent tortuosity values for di erent transport processes taking place in the same system. In order to avoid running into unclear interpretations, we pro- pose a set of tortuosity rules, which relate this concept only to the microscale geometry. On the basis of these rules, we examine the pertinence of introduc- ing the tortuosity concept in mass di usion with and without chemical reaction and convection in porous media. The upscaling process is achieved using the method of volume averaging. The results from this analysis show that e ective transport coecients (including tortuosity) can be expressed in terms of lters of the microscale information. Indeed, di erent transport processes can involve the same type of lters, but the nature of the information that passes through them is what characterizes each type of transport. The role of tortuosity in upscaling is therefore a lter that should only capture the information related to the microstructure of a system.

Publication Date
Fall December 14, 2009
Citation Information
Francisco J. Valdes-Parada, Mark L. Porter and Brian D. Wood. "Should tortuosity still be used in upscaling?" AGU (2009)
Available at: http://works.bepress.com/francisco_j_valdes_parada/38/