The Influence of Crystal Size Distributions on the Rheology of Magmas: New Insights From Analog Experiments

This study examines the influence of particle-size distributions on the rheology of particle suspensions by using analog experiments with spherical glass beads in silicone oil as a magma equivalent. The analyses of 274 individual particle-bearing suspensions of varying modality (unimodality, bimodality, trimodality, and tetramodality), as well as of polymodal suspensions with specific defined skewness and variance, are the first data set of its kind and provide important insights into the relationship between the solid particles of a suspension and its rheological behavior. Since the relationship between the rheology of particle-bearing suspensions and its maximum packing fraction m is well established by several theoretical models, the results of the analog experiments of this study reveal that the polydispersity exerts the largest influence on m. Consequently, the estimation of the polydispersity of a particle-size distribution is essential for estimating the viscosity of that given suspension.