Long time statistics of prolate spheroids dynamics in a turbulent channel flow

Michel, Antoine; Arcen, Boris

doi:10.1016/j.ijmultiphaseflow.2020.103525

Cited by 3 publications

(5 citation statements)

References 40 publications

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“…Periodic boundary conditions are applied in the and directions (statistically homogeneous directions) and a no-slip/no-penetration condition is enforced at . The numerical method is described by Michel & Arcen (2021 a ), only its main characteristics are presented hereafter. Similarly to the finite difference code used by Vreman & Kuerten (2014), the spatial derivatives appearing in (2.1) and (2.2) are approximated using fourth-order schemes in the streamwise and spanwise directions, while second-order schemes are used in the wall-normal direction.…”

Section: Simulation Set-upmentioning

confidence: 99%

“…After the particles are released in the turbulent flow, their metrics are collected every iterations, corresponding to an average time interval of in wall units. The same methodology as the one presented in Michel & Arcen (2021 a ) was used to avoid the statistical bias due to transient effects. First, the temporal evolution of the entropy parameter (Picano, Sardina & Casciola 2009) was computed to determine the time required by the particle distribution to reach a statistically steady state.…”

Section: Simulation Set-upmentioning

confidence: 99%

“…The methodology relies on DNS of the turbulent flow, coupled with Lagrangian particle tracking. To obtain reliable data, simulations are conducted until the particle distribution has reached a statistically steady state before computing the dispersed phase statistics (Michel & Arcen 2021 a ). Using this methodology, the concentration profiles and preferential orientation of inertial ellipsoids were examined up to (Michel & Arcen 2021 b ).…”

Section: Introductionmentioning

confidence: 99%

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Translational and angular velocities statistics of inertial prolate ellipsoids in a turbulent channel flow up to Re_τ = 1000

Michel

Arcen

2023

J. Fluid Mech.

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Direct numerical simulations of the turbulent flow in a channel are conducted up to $Re_{\tau }=1000$ to examine the influence of the friction Reynolds number on the translational and angular velocities of inertial, prolate ellipsoids. The quadrant distribution of the turbulent events seen by the particles is not significantly affected by the value of $Re_{\tau }$ , but subtle modifications take place, depending on the position in the channel and on the particle relaxation time. Overall, the influence of $Re_{\tau }$ on the first and second statistical moments of the ellipsoids translational velocity is the same as that observed for the fluid velocity. The weak dependence of these statistics to the particle shape previously observed at low Reynolds number remains at higher values of $Re_{\tau }$ . Similarly, the mean and root mean square (r.m.s.) of the angular velocity of the fluid seen by the particles weakly depend on particle shape and they have the same dependence to $Re_{\tau }$ as the angular velocity statistics of the carrier fluid. Particle angular velocity statistics are more strongly affected by the flow Reynolds number due to the evolution of the complex shape and inertia dependent rotation orbits with $Re_{\tau }$ . In the near-wall region the average angular velocity of weakly inertial ellipsoids increases with $Re_{\tau }$ due to their stronger alignment with the mean fluid vorticity. Furthermore, the r.m.s. of the wall-normal component of the angular velocity of more inertial ellipsoids increases with $Re_{\tau }$ owing to the larger fluctuations of the angle between the particle major axis and the velocity-gradient plane.

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Section: Simulation Set-upmentioning

confidence: 99%

Section: Simulation Set-upmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Translational and angular velocities statistics of inertial prolate ellipsoids in a turbulent channel flow up to Re_τ = 1000

Michel

Arcen

2023

J. Fluid Mech.

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“…In the earlier studies on spheroids in TCF without gravity, particles with large particle inertia have pronounced slip velocities relative to the fluid velocity in the buffer layer and core region, where the slip velocity is enhanced as particle inertia increases (Zhao et al. 2014; Michel & Arcen 2021). This pronounced slip velocity is mainly induced by the intense turbulent fluctuations near the wall (Marchioli & Soldati 2002; Zhao et al.…”

Section: Introductionmentioning

confidence: 98%

“…2018; Yuan et al. 2018 a , b ; Yang, Zhao & Andersson 2020; Michel & Arcen 2021, 2023) and particle-resolved (PR) direct numerical simulations (DNSs) (Uhlmann 2008; Do-Quang et al. 2014; Ardekani et al.…”

Section: Introductionmentioning

confidence: 99%

Effect of fluid inertial torque on the rotational and orientational dynamics of tiny spheroidal particles in turbulent channel flow

Cui,

Qiu,

Jiang

et al. 2023

J. Fluid Mech.

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Rotation and orientation of non-spherical particles in a fluid flow depend on the hydrodynamic torque they experience. However, little is known about the effect of the fluid inertial torque on the dynamics of tiny inertial spheroids in turbulent channel flows, as only Jeffery torque has been considered in previous studies by point-particle direct numerical simulations. In this study, we investigate the rotation and orientation of tiny spheroids with both fluid inertial torque and Jeffery torque in a turbulent channel flow. By comparing with the case in the absence of fluid inertial torque, we find that the rotational and orientational dynamics of spheroids is significantly affected by the fluid inertial torque when the Stokes number, which is non-dimensionalized by fluid viscous time scale, is larger than the critical value $St_c\approx 2$ , indicating that the fluid inertial torque is non-negligible for most particle cases considered in earlier studies. In contrast to the earlier findings considering only Jeffery torque (Challabotla et al., J. Fluid Mech., vol. 776, 2015, p. R2), we find that prolate (oblate) spheroids with a large Stokes number tend to tumble (spin) in the streamwise–wall-normal plane in a thinner region near the wall due to the presence of the fluid inertial torque. Approaching the channel centre, the flow shear gradually vanishes, but the velocity difference between local fluid and particles is still pronounced and increasing as particle inertia grows. As a result, in the core region, fluid inertial torque is dominant and drives the particles to align with its broad side normal to the streamwise direction rather than a random orientation observed in earlier studies without fluid inertial torque. Meanwhile, the presence of fluid inertial torque enhances the tumbling rates of spheroids in the core region. In addition, the effect of fluid inertial force on the dynamics of spheroids is also examined in this study, but the results indicate the effect of fluid inertial force is weak. Our findings imply the importance of fluid inertial torque in modelling the dynamics of inertial non-spherical particles in turbulent channel flows.

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Reynolds number effect on the concentration and preferential orientation of inertial ellipsoids

Michel

Arcen

2021

Phys. Rev. Fluids

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Long time statistics of prolate spheroids dynamics in a turbulent channel flow

Cited by 3 publications

References 40 publications

Translational and angular velocities statistics of inertial prolate ellipsoids in a turbulent channel flow up to Re_τ = 1000

Translational and angular velocities statistics of inertial prolate ellipsoids in a turbulent channel flow up to Re_τ = 1000

Effect of fluid inertial torque on the rotational and orientational dynamics of tiny spheroidal particles in turbulent channel flow

Reynolds number effect on the concentration and preferential orientation of inertial ellipsoids

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Long time statistics of prolate spheroids dynamics in a turbulent channel flow

Cited by 3 publications

References 40 publications

Translational and angular velocities statistics of inertial prolate ellipsoids in a turbulent channel flow up to Re τ = 1000

Translational and angular velocities statistics of inertial prolate ellipsoids in a turbulent channel flow up to Re τ = 1000

Effect of fluid inertial torque on the rotational and orientational dynamics of tiny spheroidal particles in turbulent channel flow

Reynolds number effect on the concentration and preferential orientation of inertial ellipsoids

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Translational and angular velocities statistics of inertial prolate ellipsoids in a turbulent channel flow up to Re_τ = 1000

Translational and angular velocities statistics of inertial prolate ellipsoids in a turbulent channel flow up to Re_τ = 1000