Studies in the flow of granular materials

Citation

Nguyen, Tanh Van (1980) Studies in the flow of granular materials. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/dm6x-9s32. https://resolver.caltech.edu/CaltechETD:etd-12062006-150937

Abstract

A number of problems related to the flow of cohesionless granular materials in hoppers are investigated.

An approximate solution to the flow of granular materials in a conical hopper is presented. The material is modeled as a rigid-perfectly plastic continuum which satisfies the Mohr-Coulomb yield condition. Unknown geometries of the upper and lower free surfaces are determined from the stress-free conditions. The results are compared to those based on different constitutive postulates as well as to experimental observations. The computed mass flow rate and wall stress compare well with the experimental measurements made with small and full size hoppers.

The flow field in a hopper with a vertical bin is observed to gain a better understanding of the details of the flow field. The observations seem to correspond to the recent results obtained by other investigators using X-ray radiography.

The funnel flow regime in hoppers is studied in detail. The different types of flow which exist are identified and classified. The possibility of having a transition from one type of flow into another one is recorded as a function of the material properties and hopper geometry. Finally, the boundary between the moving and stagnant material is studied as a function of the hopper geometry. Other parameters such as the effect of the hopper thickness and wall roughness on the flow field are also studied.

Thesis Files