To closely study the influence of shape, the particles considered are equal in volume, and therefore cover a range of Reynolds numbers, limited to. The data for the investigations are obtained by surface resolved simulations of superellipsoids, applying the homogenized lattice Boltzmann method. The aim is to find models describing the drag coefficient and settling velocity, based on this extended set of shape parameters. This work extends the list of considered parameters by, e.g., convexity and roundness and evaluates the relevance of each. This does not cover all relevant effects, since the process of settling for arbitrarily shaped particles is highly complex. To date, the only considered shape parameters are derivatives of the axis lengths and the sphericity. In this work, a constructive and data-driven approach is presented to obtain new drag correlations. Models in the available literature usually fit a given function to experimental data.
There is a need to obtain equations specifically developed for plastic particles, especially for fibres, and for the atmospheric compartment.Ī detailed knowledge of the influence of a particle’s shape on its settling behavior is useful for the prediction and design of separation processes. This work shows that the behaviour of irregular particles is not adequately predicted using as descriptor the diameter of the sphere with the same volume as the particle. The derivation of Stoke's diameter based on 3D morphological descriptors is explained and the proxies that can be used if only 2D projected images are available is discussed. The particle size directly linked to the environmental fate of microplastics is the Stoke's diameter. Three dimensionless parameters, namely equancy, platiness and elongation describe any particle shape with reference on the basic 3D (sphere), 2D (plate) and 1D (rod) shapes. This work presents a morphological description based on the lengths of the smallest enclosing orthogonal parallelepiped.
However, data intercomparison requires unambiguous classifications. The morphological description of microplastic particles is mostly based on subjective descriptors. Várkonyi and Domokos (2006) established the existence of Rows (S) denote number of stable equilibria, columns (U) denote number of unstable equilibria. Equilibrium classes for 3D bodies: examples for some characteristic shapes.
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