Fundamentally-based dimensionless numbers for predicting particle detachment from porous media

ENVR 91

John A. Bergendahl, Department of Civil & Environmental Engineering, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609 and Domenico Grasso, Picker Engineering Program, Smith College, Northampton, MA 01063.
Particle detachment from surfaces in natural and model systems with chemical and physical perturbations has been observed by many researchers. In this work, a mathematical construct based on a fundamental approach is used to quantify thermodynamic and hydrodynamic components of the overall stability of attached particles. The force and moment balance is coupled with an extension of classical DLVO theory to find mobilization conditions. The physically-significant dimensionless numbers that describe detachment were found using dimensional analysis with Buckingham Pi theorem. These dimensionless numbers were coupled with the authors' previous work that determines conditions favorable for detachment. The relevance and utility of these dimensionless numbers are illustrated through use of published particle detachment results. This approach using dimensionless groups provides a technique to determine conditions for detachment in engineered and natural porous media. This technique will have utility in many engineering applications where fluid/particle separation needs to be predicted.