TY - JOUR
T1 - Strong alignment of prolate ellipsoids in Taylor-Couette flow
AU - Assen, Martin P.A.
AU - Ng, Chong Shen
AU - Will, Jelle B.
AU - Stevens, Richard J.A.M.
AU - Lohse, Detlef
AU - Verzicco, Roberto
N1 - Funding Information:
This work is part of the research programme of the Foundation for Fundamental Research on Matter with project number 16DDS001, which is financially supported by the Netherlands Organisation for Scientific Research (NWO). R.J.A.M.S. acknowledges the financial support from ERC (European Research Council) Starting Grant No. 804283 UltimateRB.
Publisher Copyright:
© The Author(s), 2022. Published by Cambridge University Press.
PY - 2022/3/25
Y1 - 2022/3/25
N2 - We report on the mobility and orientation of finite-size, neutrally buoyant, prolate ellipsoids (of aspect ratio) in Taylor-Couette flow, using interface-resolved numerical simulations. The set-up consists of a particle-laden flow between a rotating inner and a stationary outer cylinder. The flow regimes explored are the well-known Taylor vortex, wavy vortex and turbulent Taylor vortex flow regimes. We simulate two particle sizes and, denoting the particle major axis and the gap width between the cylinders. The volume fractions are and, respectively. The particles, which are initially randomly positioned, ultimately display characteristic spatial distributions which can be categorised into four modes. Modes (i) to (iii) are observed in the Taylor vortex flow regime, while mode (iv) encompasses both the wavy vortex and turbulent Taylor vortex flow regimes. Mode (i) corresponds to stable orbits away from the vortex cores. Remarkably, in a narrow range, particles get trapped in the Taylor vortex cores (mode (ii)). Mode (iii) is the transition when both modes (i) and (ii) are observed. For mode (iv), particles distribute throughout the domain due to flow instabilities. All four modes show characteristic orientational statistics. The focus of the present study is on mode (ii). We find the particle clustering for this mode to be size-dependent, with two main observations. Firstly, particle agglomeration at the core is much higher for compared with. Secondly, the range for which clustering is observed depends on the particle size. For this mode (ii) we observe particles to align strongly with the local cylinder tangent. The most pronounced particle alignment is observed for at around. This observation is found to closely correspond to a minimum of axial vorticity at the Taylor vortex core and we explain why.
AB - We report on the mobility and orientation of finite-size, neutrally buoyant, prolate ellipsoids (of aspect ratio) in Taylor-Couette flow, using interface-resolved numerical simulations. The set-up consists of a particle-laden flow between a rotating inner and a stationary outer cylinder. The flow regimes explored are the well-known Taylor vortex, wavy vortex and turbulent Taylor vortex flow regimes. We simulate two particle sizes and, denoting the particle major axis and the gap width between the cylinders. The volume fractions are and, respectively. The particles, which are initially randomly positioned, ultimately display characteristic spatial distributions which can be categorised into four modes. Modes (i) to (iii) are observed in the Taylor vortex flow regime, while mode (iv) encompasses both the wavy vortex and turbulent Taylor vortex flow regimes. Mode (i) corresponds to stable orbits away from the vortex cores. Remarkably, in a narrow range, particles get trapped in the Taylor vortex cores (mode (ii)). Mode (iii) is the transition when both modes (i) and (ii) are observed. For mode (iv), particles distribute throughout the domain due to flow instabilities. All four modes show characteristic orientational statistics. The focus of the present study is on mode (ii). We find the particle clustering for this mode to be size-dependent, with two main observations. Firstly, particle agglomeration at the core is much higher for compared with. Secondly, the range for which clustering is observed depends on the particle size. For this mode (ii) we observe particles to align strongly with the local cylinder tangent. The most pronounced particle alignment is observed for at around. This observation is found to closely correspond to a minimum of axial vorticity at the Taylor vortex core and we explain why.
KW - rotating turbulence
KW - particle/fluid flow
KW - UT-Hybrid-D
UR - http://www.scopus.com/inward/record.url?scp=85124214645&partnerID=8YFLogxK
U2 - 10.1017/jfm.2021.1134
DO - 10.1017/jfm.2021.1134
M3 - Article
SN - 0022-1120
VL - 935
JO - Journal of fluid mechanics
JF - Journal of fluid mechanics
M1 - A7
ER -