Author : Himani Garg
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (124 download)
Book Synopsis Particle Laden Inhomogeneous Elastic Turbulence by : Himani Garg
Download or read book Particle Laden Inhomogeneous Elastic Turbulence written by Himani Garg and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laboratory experiments show that, even in very dilute solutions, the interaction of polymers with fluid flows can dramatically change the properties of turbulent flows or, if the flow is laminar, can trigger a new sort of irregular motion named “elastic turbulence”. Flows in such a dynamical regime are promising for enhancing mixing efficiency in microfluidic applications, which often involve the presence of suspended finite-size impurities, like small and heavy solid particles. The understanding of particle dispersion in high-Reynolds number flows of Newtonian, as well as non-Newtonian, fluids were addressed by previous investigations, and it is a subject of interest both at a fundamental level and for applications, e.g., environmental or industrial ones. However, the dynamics of particles in elastic turbulent flows are still quite unexplored.The present study aims at investigating the aggregation properties of pointlike material particles (heavier than the carrying fluid) in viscoelastic fluids in elastic turbulence conditions (i.e. in the limit of vanishing fluid inertia and large elasticity). We carry out extensive direct numerical simulations of the periodic Kolmogorov mean shear flow of two-dimensional dilute polymer solutions described by the Oldroyd-B model. Both the small- and large-scale features of the resulting inhomogeneous particle distribution are examined, focusing on their connection with the underlying flow structure. Our analysis reveals that particles are preferentially clustered in regions of instantaneously maximally stretched polymers. The intensity of such a phenomenon depends on the interplay, parametrized by the Stokes number, between the particle inertia and the typical time scale associated with the elastic turbulence flow, and is the largest for intermediate values of particle inertia.In particular, it is shown that the preferential concentration of inertial particle suspensions in such turbulent-like flows follow from the dissipative nature of their dynamics. We provide a quantitative characterization of this phenomenon (using correlation and Kaplan-Yorke dimension) that allows to relate it to the accumulation of particles in filamentary highly strained flow regions producing clusters of fractal dimension slightly above 1.At larger scales, particles are found to undergo turbophoretic-like segregation along the non-homogeneity direction of the flow. Indeed, our results indicate that the particle distribution is strongly related to the mean turbulent-like structures of the flow. As an effect of turbophoresis, average density profiles peak in the regions of lowest turbulent eddy diffusivity. The large-scale inhomogeneity of the particle distribution is interpreted in the framework of a model derived in the limit of small, but finite, particle inertia. The qualitative characteristics of different observables (such as root-mean-square deviation of the particle distribution, relative to the uniform one) are, to a good extent, independent of the flow elasticity. When increased, the latter is found, however, to slightly reduce the globally averaged degree of turbophoretic unmixing.
