Porous Media Theory

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The porous media theory ( TPM ) is a continuum mechanical concept. It describes systems that consist of a porous solid , whose pores are flowed through by one or more fluids or are gas-filled. The theory has applications, for example, in soil mechanics, for example in consolidation or biology.

Basics

In the TPM, the material areas of the individual sub-bodies are not spatially separated from one another. Instead, each part of the body is assigned a specific volume fraction at each point . In general, every part of the body has its own movement function . The movement functions are defined across the entire material area and overlap.

history

The Viennese professor Paul Fillunger was the first to add the concept of volume fractions to a solid-fluid model (1913). In his publication he dealt with the buoyancy of dams. It already contained the concept of effective tensions used today. The buoyancy equation used by Fillunger, however, contained a serious flaw which was noticed by Karl von Terzaghi in the early 1930s . This led to an argument between the two scientists.

Karl von Terzaghi founded modern soil mechanics as an independent engineering science with his theories and experiments on soil consolidation , earth pressure , load-bearing capacity and soil stability . Together with his colleague Otto Karl Fröhlich , he published a book in 1936 on the consolidation of porous solids. In Fillunger's view, this book was largely sloppily written. Fillunger used this to return the favor to von Terzaghi.

The scandal came when Fillunger published a pamphlet at the end of 1936 in which he attempted to discredit von Terzaghi and Fröhlich. In this publication, Fillunger described the consolitation problem as a two-phase system with superimposed movements. His approach corresponded to today's standard, but it was hardly noticed by the scientific community.

Ray M. Bowen described porous solids in the 1980s by adding the concept of volume fractions to mixing theory .

Individual evidence

  1. ↑ Wolfgang Ehlers: Challenges of Porous Media Models in Geo- and Biomechanical Engineering including Electro-Chemically Active Polymers and Gels . In: International Journal of Advances in Engineering Sciences and Applied Mathematics . Vol. 1, 2009, pp. 1–24 , doi : 10.1007 / s12572-009-0001-z ( PDF 1.84 MB ).
  2. ↑ a b c d Reint de Boer : From Leonardo's vine to high-tech applications . In: Unique items from Essen . tape 23 , 2004, pp. 10–21 ( PDF 1.11 MB ).

literature

Wolfgang Ehlers: Basic Concepts in the Theory of Porous Media. (pdf; 13.9 MB) December 6, 1995, accessed on September 9, 2010 .