TRAIL: A novel approach for studying the aerodynamics of ice particles

Abstract

A novel experimental approach for studying the aerodynamics of ice particles is presented. The Trajectory Reconstruction Algorithm implemented through Image anaLysis (TRAIL) produces digital reconstructions of the trajectory and orientation of 3D-printed analogues of ice particles that fall through a quiescent viscous liquid. Data extracted from this analysis can be used to test fall speed parametrisations and investigate the preferred orientation of analogues with complex irregular geometries. Experiments using thin circular discs are used to validate this approach. Measurements from a case study in which an analogue of an aggregate ice particle is used are also reported. Data extracted from the analysis clearly demonstrate important, but poorly understood, aspects of the aerodynamics of atmospheric ice particles. For example, the orientation that the analogue adopts in free fall is shown to depend not only on the geometric shape of the particle, but also on the Reynolds number at which it falls. In addition, measurements of the drag coefficient indicate that the accuracy of fall speed parametrisations reduces at high Reynolds number due to the onset of unsteady motions.

Rising and Sinking in Resonance: Mass Distribution Critically Affects Buoyancy-Driven Spheres via Rotational Dynamics

“…Clearly, such an offset can also be expected to occur in a host of practical applications, where particle properties are rarely ever uniform. This concerns, for example, the falling of dandelion seeds [30] and snowflakes [31][32][33][34][35], the sedimentation behavior of sand grains and stones [36,37], chemical and biological reactors with (inverse) fluidized beds [38], as well as the transport of microplastic in the oceans [39]. Moreover, the practical relevance is rooted in the fact that we find that even small values of γ can affect the kinematics and dynamics of spherical particles significantly.…”

Numerical analysis of the wake of complex-shaped snow particles at moderate Reynolds number

“…The trajectory of falling analogs was recorded using a system of three synchronized cameras positioned to have orthogonal views of the tank. An algorithm (the Trajectory Reconstruction Algorithm implemented through Image anaLysis, TRAIL) allowed the reconstruction of the timeresolved trajectory and orientation of falling analogs over the recorded region (approximately 200 × 200 × 200 mm in size) [McCorquodale and Westbrook 2021a]. With this approach, it was possible to determine the precise orientation adopted by each particle in the free-fall and to represent these positions digitally with a mesh of triangular facets that correspond to the particle surface.…”

Rising and Sinking in Resonance: Probing the critical role of rotational dynamics for buoyancy driven spheres

“…This concerns e.g. the falling of dandelion seeds [28] and snowflakes [29][30][31][32][33], the sedimentation behaviour of sand grains and stones [34,35], chemical and biological reactors with (inverse) fluidized beds [36], as well as the transport of micro-plastic in the oceans [37]. The practical relevance is moreover rooted in the fact that we find that even small values of γ can affect the kinematics and dynamics of spherical particles significantly.…”