Abstract
External forces lead to granular flow under the condition that the applied shear stress reaches the yield (shear) stress while another stress must be maintained for continuous flow in steady state. Most studies in granular physics focus on dry granular materials and their flow rheology. However, wet granular materials are ubiquitous in geology and many real world applications where interstitial liquid is present between the grains. There are several proposals for flow rules of dry and wet granular materials available in the literature. These flow rules differ in complexity and in the number of parameters, which are combined in the equations. The main focus areas of my research are (i) the formulation of suitable constitutive equations for the hydrodynamic densitystressstrain relations, specifically for wet granular materials, (ii) the deduction of the constitutive equations from discrete element simulations, and (iii) the validation of the micromacro transition with numerical, theoretical and experimental results. The geometrical setup of splitbottom shear cell used in my research is most appropriate for assessing the shear band originating from the split position that widens near the free surface.
My research proposes a modified generalized flow rule/rheology to close the fundamental conservation laws for mass and momentum. Subsequently, a correlation is developed between the micro parameters and the {steady state cohesion in the limit} of very low confining pressure. Another aspect of studying unsaturated granular media is the movement of interstitial liquid due to the rupture of existing and formation of new liquid bridges. Shearing a wet granular system causes a redistribution and transport of the interstitial liquid. The liquid transport can be modeled by a diffusion equation with a spacedependent diffusive coefficient in the split bottom geometry. Alternatively, it is shown here that this is an advectivediffusive process with constant diffusivity coefficient and a spacedependent drift, when transformed to an appropriate set of variables that can be solved analytically. The final chapter of this thesis concerns the experimental work exploring the surface flow profile for different dry and wet granular materials.
My research proposes a modified generalized flow rule/rheology to close the fundamental conservation laws for mass and momentum. Subsequently, a correlation is developed between the micro parameters and the {steady state cohesion in the limit} of very low confining pressure. Another aspect of studying unsaturated granular media is the movement of interstitial liquid due to the rupture of existing and formation of new liquid bridges. Shearing a wet granular system causes a redistribution and transport of the interstitial liquid. The liquid transport can be modeled by a diffusion equation with a spacedependent diffusive coefficient in the split bottom geometry. Alternatively, it is shown here that this is an advectivediffusive process with constant diffusivity coefficient and a spacedependent drift, when transformed to an appropriate set of variables that can be solved analytically. The final chapter of this thesis concerns the experimental work exploring the surface flow profile for different dry and wet granular materials.
Original language  English 

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Award date  26 Jan 2018 
Place of Publication  Enschede 
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Print ISBNs  9789036544689 
DOIs  
Publication status  Published  26 Jan 2018 