SCARLET-1.0: SpheriCal Approximation for viRtuaL aggrEgaTes

Abstract. Aggregation of particles occurs in a large variety settings and is therefore the focus many disciplines, e.g., Earth environmental sciences, astronomy, meteorology, pharmacy, food industry. In particular, volcanology, ash aggregation deeply influences sedimentation volcanic atmosphere during after eruption, affecting accuracy model predictions evaluation hazard risk assessments. It thus very important to provide an exhaustive description outcome process, starting from its basic geometrical features such as position space components overall porosity final object. Here we present SCARLET-1.0, MATLAB package specifically created 3D virtual reconstruction for aggregates generated central collision processes. centrally oriented collisions, build up their own structure around first particle (the core), acting seed. This appropriate turbulent flows which show different degrees coupling with respect eddies. SCARLET-1.0 belongs class sphere-composite algorithms, family algorithms that approximate complex shapes terms set nonoverlapping spheres. The conversion surface equivalent then allows analytical detection intersections between objects aggregate together. Thus, provided list colliding sizes shapes, places each element vector core, minimizing distances centers mass. user can play parameters control minimization process. Among them most ones are cone investigation (Ω), number rays per (Nr), orientations object (No). All described using Standard Triangulation Language (STL) format, current standard printing. one key results unlimited range applications package. main code representation object, size, porosity, density, associated STL file. addition, be potentially printed. As example, has been applied here ellipsoid–ellipsoid collisions more specific analysis aggregation. application two ellipsoids less than 20 % if flatness elongation greater or equal 0.5. Higher values porosities (up 40 %–50 %) instead found needle-like extremely flat shapes. second application, reconstruct evolution time characterized by inner structures. We find whose population narrow distribution tend rapidly reach plateau porosity. reproduce observed densities, almost no compaction necessary result suggests how not well maximum packing condition.