On the orientational dependence of drag experienced by spheroids

Sanjeevi, Sathish K. P.; Padding, JT Johan

doi:10.1017/jfm.2017.239

Cited by 59 publications

(63 citation statements)

References 17 publications

(15 reference statements)

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“…In the present work, we use a D3Q19, MRT lattice Boltzmann method to simulate the fluid flow. The numerical method is adequately explained and validated in our previous works . The evolution of particle distribution function ∣ f 〉 is computed as

∣ f ((),, bold-italicr + e_{α} normalΔ t, t + normalΔ t) false〉 = ∣ f ((), bold-italicr, t) false〉 - M^{- 1} \overset{S}{true} ((), ∣ m ((), bold-italicr, t) false〉 - ∣ m^{(eq)} ((), bold-italicr, t) false〉),

for position r with discrete velocities e α in directions α = 1, 2…, 19.…”

Section: Methodsmentioning

confidence: 99%

“…Recently, we developed drag, lift, and torque closures for three different nonspherical particles from the viscous Stokes regime upto the high Re regime of Re = 2000, involving complex, unsteady flows . In an earlier work, we reported the interesting finding that the drag coefficient C D at different incident angles ϕ follows a sine‐squared scaling given by

C_{normalD, ϕ} = C_{normalD, ϕ = 0^{°}} + ((), C_{normalD, ϕ = 90^{°}} - C_{normalD, ϕ = 0^{°}}) \sin^{2} ϕ .

…”

Section: Introductionmentioning

confidence: 99%

“…The abovementioned scaling laws must be mathematically true in the Stokes regime due to linearity of the flow fields. However, their validity in the inertial regimes is primarily due to an interesting pattern of pressure distribution contributing to the drag and lift for different incident angles . In Equations , the drag coefficients at incident angles of 0° and 90° still depend on particle shape and Reynolds number.…”

Section: Introductionmentioning

confidence: 99%

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Hydrodynamic forces on monodisperse assemblies of axisymmetric elongated particles: Orientation and voidage effects

Sanjeevi

Padding

2020

AIChE Journal

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This work provides a recipe for creating drag, lift and torque closures for static assemblies of axisymmetric, non-spherical particles. Apart from Reynolds number Re and solids volume fraction ǫ s , we propose four additional parameters to characterize the flow through non-spherical particle assemblies. Two parameters consider the mutual orientations of particles (the orientation tensor eigenvalues S 1 and S 2 ) and two angles represent the flow direction (polar and azimuthal angles α and β). Interestingly, we observe that the hydrodynamic forces on the particles are independent of the mutual particle orientations. Rather, the most important parameter representing the particle configuration itself is the incident angle φ of the individual particles with respect to the incoming flow. Moreover, we observe that our earlier finding of sine-squared scaling of drag for isolated particles (Sanjeevi & Padding 2017) holds on average even for a multiparticle system in both the viscous and inertial regimes. Similarly, we observe that the average lift for a multiparticle system follows sine-cosine scaling, as is observed for isolated particles. Such findings are very helpful since the pressure drop of a packed bed or porous media can be computed just with the knowledge of orientation distribution of particles and their drag at φ = 0 • and φ = 90 • for a given Re and ǫ s . With the identified dependent parameters, we propose drag, lift and torque closures for multiparticle systems.

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∣ f ((),, bold-italicr + e_{α} normalΔ t, t + normalΔ t) false〉 = ∣ f ((), bold-italicr, t) false〉 - M^{- 1} \overset{S}{true} ((), ∣ m ((), bold-italicr, t) false〉 - ∣ m^{(eq)} ((), bold-italicr, t) false〉),

for position r with discrete velocities e α in directions α = 1, 2…, 19.…”

Section: Methodsmentioning

confidence: 99%

C_{normalD, ϕ} = C_{normalD, ϕ = 0^{°}} + ((), C_{normalD, ϕ = 90^{°}} - C_{normalD, ϕ = 0^{°}}) \sin^{2} ϕ .

…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hydrodynamic forces on monodisperse assemblies of axisymmetric elongated particles: Orientation and voidage effects

Sanjeevi

Padding

2020

AIChE Journal

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“…Laws (15) and (16) obtained using linearity of Stokes equations might be valid for other aspect ratios. Indeed the linearity of Stokes equations remains valid for all aspect ratios and these laws have proven to be valid even for spheroids of high aspect ratio [53]. The assumption C Dθ=0 • ≈ 1/2C Dθ=90 • is also supposed to give more accurate results as L/D increases [4].…”

Section: Simple Laws For the Hydrodynamic Force And Torquementioning

confidence: 99%

“…Sanjeevi and Padding [53] studied recently the flow past oblate spheroids. They observed that (8) and (9) obtained in the Stokes regime match well numerical results even in inertial −-− (6) and (7).…”

Section: Simple Laws For the Hydrodynamic Force And Torquementioning

confidence: 99%

Inertial flow past a finite-length axisymmetric cylinder of aspect ratio 3: Effect of the yaw angle

et al. 2019

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We study the flow past a finite-length yawed 3D cylinder by a Finite Volume / Fictitious Domain (FV/FD) method developed in [63]. We validate our non-boundary-fitted method against boundary-fitted numerical results for a finite-length cylinder whose axis is parallel to the streamwise direction. Drag and lift forces exerted on the cylinder and vortex shedding onset and frequency are carefully analysed. Satisfactory agreement with published results give strong confidence in the numerical methodology provided the boundary layer is accurately resolved. Then, we carry out a detailed study of the flow past a yawed cylinder of aspect ratio L/D = 3 (where L is the cylinder length and D is the cylinder diameter) at moderate Reynolds numbers (25 Re 250). We show that the wake pattern depends strongly on Re and the yaw angle θ with respect to the streamwise direction. Various regimes are encountered including standing-eddy pattern, steady shedding of one and two pairs of counter-rotating vortices, periodic shedding of two pairs of counter-rotating vortices and unsteady shedding of hairpin shaped vortices. The standing-eddy pattern regime shows different forms of behaviour and symmetry as function of θ. Hydrodynamic forces exerted on the cylinder are well approximated by laws derived in the Stokes flow regime (benefitting from the linearity of the equations), even for moderate Reynolds numbers. This result is in agreement with recent findings of Sanjeevi and Padding [53] who studied the flow past spheroidal particles.For the highest Reynolds numbers (Re = 150, 200, 250) we show that simple force laws can be derived from simple geometrical assumptions. These simple laws yield a satisfactory match with our numerical results.

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Anisotropic Optical and Frictional Properties of Langmuir–Blodgett Film Consisting of Uniaxially‐Aligned Rod‐Shaped Cellulose Nanocrystals

Chae

Ngo

Chen

et al. 2020

Adv Materials Inter

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Langmuir-Blodgett (LB) film deposition gives an opportunity to control the packing density and orientation of anisotropic nanoparticles at a monolayer level, allowing accurate characterization of their anisotropic material properties. The uniaxial deposition of rod-shaped cellulose nanocrystals (CNCs) over a macroscopically large area is achieved by aligning the long axis of CNCs on the LB trough with the direction of the maximum drag force within the meniscus during the vertical pulling of the substrate from the LB trough. On the uniaxially-aligned LB films, anisotropic linear and non-linear optical properties of CNCs are obtained using Mueller matrix spectroscopy and sum frequency generation spectroscopy, respectively, and explained with time-dependent density functional theory calculations. Also, the frictional anisotropy of the LB film is measured using atomic force microscopy and explained theoretically. The findings of this study will be valuable for preparation of anisotropic nanoparticle thin films with uniform arrangements and utilization of their anisotropic material properties.

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On the orientational dependence of drag experienced by spheroids

Cited by 59 publications

References 17 publications

Hydrodynamic forces on monodisperse assemblies of axisymmetric elongated particles: Orientation and voidage effects

Hydrodynamic forces on monodisperse assemblies of axisymmetric elongated particles: Orientation and voidage effects

Inertial flow past a finite-length axisymmetric cylinder of aspect ratio 3: Effect of the yaw angle

Anisotropic Optical and Frictional Properties of Langmuir–Blodgett Film Consisting of Uniaxially‐Aligned Rod‐Shaped Cellulose Nanocrystals

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