2016/07/05 by Sholpan Sumbekova, Alain Cartellier, Alberto Aliseda +1 · 1 citation
Physics and Astronomy · #physics.flu-dyn
paper · pdf · doi:10.1103/physrevfluids.2.024302
published as Phys. Rev. Fluids 2, 024302 (2017)
arxiv created 2016/07/05 · arxiv updated 2017/02/15
Turbulent flows laden with inertial particles present multiple open questions and are a subject of great interest in current research. Due to their higher density compared to the carrier fluid, inertial particles tend to form high concentration regions, i.e. clusters, and low concentration regions, i.e. voids, due to the interaction with the turbulence. In this work, we present an experimental investigation of the clustering phenomenon of heavy sub-Kolmogorov particles in homogeneous isotropic turbulent flows. Three control parameters have been varied over significant ranges: Reλ ∈ [170 - 450], St∈ [0.1 - 5] and volume fraction ϕv∈ [2× 10-6 - 2× 10-5]. The scaling of clustering characteristics, such as the distribution of Voronoï areas and the dimensions of cluster and void regions, with the three parameters are discussed. In particular, for the polydispersed size distributions considered here, clustering is found to be enhanced strongly (quasi-linearly) by Reλ and noticeably (with a square-root dependency) with ϕv, while the cluster and void sizes, scaled with the Kolmogorov lengthscale η, are driven primarily by Reλ. Cluster length √(⟨ Ac ⟩) scales up to ≈ 100 η, measured at the highest Reλ, while void length √(⟨ Av ⟩) scaled also with η is typically two times larger (≈ 200 η). The lack of sensitivity of the above characteristics to the Stokes number lends support to the "sweep-stick" particle accumulation scenario. The non-negligible influence of the volume fraction, however, is not considered by that model and can be connected with collective effects.