Crack formation in drying laponite / Sujata Tarafdar in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6459–6464 Titre : Crack formation in drying laponite Type de document : texte imprimé Auteurs : Sujata Tarafdar, Auteur ; Suparna Sinha, Auteur Année de publication : 2008 Article en page(s) : p. 6459–6464 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Crack patterns Laponite Résumé : Natural clay and other granular materials form crack networks with typical patterns on desiccation. The present paper reviews a series of studies on crack patterns produced by drying laponite suspensions in different solvents, on different substrates. Laponite is a synthetic clay composed of nanosized platelets of uniform size and composition. The area covered by the cracks shows a scaling behavior with layer thickness. The salient features of the experimental observations can be reproduced by a computer simulation with a chain of springs modeling the clay. We review earlier work done on crack patterns in drying laponite, suspended in methanol as well as water. Experiments on a modification of the setup where the samples are allowed to dry in an electric field are also reviewed. We present new results done on a different geometrical arrangement of the electrodes. The crack patterns are again found to follow the symmetry of the field. Another new observation is that gelation starts earlier when suspensions with excess water are placed in an electric field. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071375x [article] Crack formation in drying laponite [texte imprimé] / Sujata Tarafdar, Auteur ; Suparna Sinha, Auteur . - 2008 . - p. 6459–6464. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6459–6464 Mots-clés : Crack patterns Laponite Résumé : Natural clay and other granular materials form crack networks with typical patterns on desiccation. The present paper reviews a series of studies on crack patterns produced by drying laponite suspensions in different solvents, on different substrates. Laponite is a synthetic clay composed of nanosized platelets of uniform size and composition. The area covered by the cracks shows a scaling behavior with layer thickness. The salient features of the experimental observations can be reproduced by a computer simulation with a chain of springs modeling the clay. We review earlier work done on crack patterns in drying laponite, suspended in methanol as well as water. Experiments on a modification of the setup where the samples are allowed to dry in an electric field are also reviewed. We present new results done on a different geometrical arrangement of the electrodes. The crack patterns are again found to follow the symmetry of the field. Another new observation is that gelation starts earlier when suspensions with excess water are placed in an electric field. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071375x

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Viscous fingering patterns and evolution of their fractal dimension / Suparna Sinha in Industrial & engineering chemistry research, Vol. 48 N° 19 (Octobre 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8837–8841 Titre : Viscous fingering patterns and evolution of their fractal dimension Type de document : texte imprimé Auteurs : Suparna Sinha, Auteur ; Sujata Tarafdar, Auteur Année de publication : 2009 Article en page(s) : pp. 8837–8841 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Viscous fingering patterns Newtonian defending fluid Castor oil Olive Résumé : We present a study of viscous fingering patterns which arise because of the instability at the interface of two fluids of dissimilar viscosities. Viscous fingering experiments were performed in a lifting Hele-Shaw cell with a Newtonian defending fluid, castor oil or olive oil, while the invading fluid is air. We focus here on the fractal dimension of the patterns and how it varies with the lifting pressure in the Hele-Shaw cell. The fractal dimension of the fluid−air interface is measured by the divider step method. It is seen that the dimension changes from a value close to one, indicating no instability, to a value around 1.6 as the pressure is increased. A change in fractal dimension with time is also observed as the pattern evolves. Measurement of the fractal dimension offers a method for quantifying the instability. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801836r [article] Viscous fingering patterns and evolution of their fractal dimension [texte imprimé] / Suparna Sinha, Auteur ; Sujata Tarafdar, Auteur . - 2009 . - pp. 8837–8841. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8837–8841 Mots-clés : Viscous fingering patterns Newtonian defending fluid Castor oil Olive Résumé : We present a study of viscous fingering patterns which arise because of the instability at the interface of two fluids of dissimilar viscosities. Viscous fingering experiments were performed in a lifting Hele-Shaw cell with a Newtonian defending fluid, castor oil or olive oil, while the invading fluid is air. We focus here on the fractal dimension of the patterns and how it varies with the lifting pressure in the Hele-Shaw cell. The fractal dimension of the fluid−air interface is measured by the divider step method. It is seen that the dimension changes from a value close to one, indicating no instability, to a value around 1.6 as the pressure is increased. A change in fractal dimension with time is also observed as the pattern evolves. Measurement of the fractal dimension offers a method for quantifying the instability. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801836r

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