Development and Validation of Particle-Phase Stress Constitutive Models for Non-Spherical Particles

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0854005Curtis, Jennifer Virtually all solid handling operations involve particles that are non-spherical in shape. However, most fundamental studies of granular material undertaken to date have involved spherical particles. Hence, there is a current significant disconnect between the model particles which are used in fundamental research studies and the characteristics of real particles dealt with in industry. While industrial practitioners comprehend fully that the influence of particle shape on particle flow behavior is significant, the role of particle shape in flowing granular systems is not understood. Hence, this proposal outlines a series of DEM simulations and complementary experiments which will result in a fundamental understanding of the influence of various specific features of particle shape on bulk particle flow behavior. In addition, results from the proposed work will yield the ability to predict general trends in flow and segregation behavior for non-spherical particles in a wide range of processes. The proposed work has three specific objectives: 1. To evaluate the quantitative accuracy of DEM simulations involving non-spherical particles modeled as collections of linked/overlapping spheres 2. To investigate the effect of particle shape on particle segregation in particle storage devices - a significant problem in industry 3. To develop and validate constitutive models for particle-phase stress of non-spherical particles that can be employed in CFD simulations The intellectual merit of the proposed work lies in the simulations and experiments, involving non-spherical interacting particles, which will be conducted, and the novel fundamental relationships and insights, pertaining to the influence of particle shape on bulk solids handling, which will be obtained. Real particle properties, not idealized smooth, round particles, must be considered before most industrially-relevant problems can be tackled. While a three-year project can not treat all aspects of real particles mixtures (e.g. particle size distribution, cohesion, electrostatic behavior, etc.), making headway on the effect of particle shape is a very significant advance in the field of granular flow. In addition, successful completion of this project fits well with the PI's longer term goal of developing first principles, predictive models that can be used for design, scale-up and optimization of particle flow processes. The proposed research will have broad impact since the research results are applicable to virtually all industrial granular flows which involve non-spherical particles. The research results will lead to improved constitutive models for CFD simulations, which are widely employed by industrial researchers. The results will also yield recommendations on ways to mitigate particle segregation during hopper discharge by altering the particle shape and/or particle size (based on equivalent volume diameter), as well as particle composition based on shape and size. Finally, the proposed research will have broad impact via involvement of students (one PhD student as well as minority undergraduate researchers) in the research, and the dissemination of the research findings to the scientific community, both through journal publications and through the education of large numbers of students and industrial personnel.