Variation of drag, lift and torque in a suspension of ellipsoidal particles

He, Long; Tafti, Danesh K.

doi:10.1016/j.powtec.2018.05.031

Cited by 32 publications

(17 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The variation in forces at different incident angles ϕ is mainly arising from the pressure forces. The same can also be confirmed from the multiparticle work of He and Tafti, which is also in line with our finding for isolated nonspherical particles …”

Section: Resultssupporting

confidence: 92%

See 1 more Smart Citation

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

Sanjeevi

Padding

2020

AIChE Journal

View full text Add to dashboard Cite

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.

show abstract

Section: Resultssupporting

confidence: 92%

“…The viscous drag reduces and pressure drag increases with increasing ϕ at low Re. The same has been confirmed for isolated particles and for a multiparticle system . The combined viscous and pressure drag components result in a drag ratio close to 1 for the considered spherocylinders at low Re.…”

Section: Resultssupporting

confidence: 73%

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

Sanjeevi

Padding

2020

AIChE Journal

View full text Add to dashboard Cite

show abstract

“…Hence this particle may experience an additional lift force and a hydrodynamic torque which can modify the particle behavior . He and Tafti performed particle‐resolved simulations of fixed random suspension of ellipsoidal particles and demonstrated that the torque and secondary forces affect the particle dynamics as the Reynolds number increases. Mema et al showed that the lift force can have significant influence on the particle velocities parallel to the direction of the gravity and the particle orientation depends on the hydrodynamic torque.…”

Section: Model Descriptionmentioning

confidence: 99%

Bubble dynamics in bubbling fluidized beds of ellipsoidal particles

Shrestha

Kuang

et al. 2019

AIChE Journal

View full text Add to dashboard Cite

This article presents a CFD-DEM study on the effect of particle shape on bubble dynamics in bubbling fluidized beds. The particles used are ellipsoids, covering from disk-type to cylinder-type. The phenomena such as bubble coalescence and splitting are successfully generated, and the results are compared with literature, showing a good agreement. The results demonstrate that the bubble forming/rising regions and patterns are influenced significantly by particle shape. Ellipsoidal particles have asymmetrical bubble patterns with two or more circulation vortices while the bubbles for spherical particles form at the bed centerline and rise through the center of the bed. Hence, the vertical mass flux at the bed centerline for spheres is always positive, and ellipsoids have negative or positive vertical mass fluxes. The solid mixing estimated based on the dispersion coefficient revealed poor mixing for ellipsoids. Spherical particles have a larger bubble size and higher bubble rising velocity than ellipsoids.

show abstract

“…The IBM procedure and implementation of boundary conditions are described in detail in Nagendra et al [58]. The method was previously applied by Viswanath et al [47,55] to bat flight, and by He and Tafti [59,60] to force and heat transfer calculations in particle suspensions. Most recently it was also applied by Windes et al [52] to the native kinematics of the H .…”

Section: Aerodynamic Analysesmentioning

confidence: 99%

Canonical description of wing kinematics and dynamics for a straight flying insectivorous bat (Hipposideros pratti)

et al. 2019

View full text Add to dashboard Cite

Bats, with highly articulated wings, are some of the most agile flyers in nature. A novel three-dimensional geometric decomposition framework is developed to reduce the complex kinematics of a bat wing into physical movements used to describe flapping flight: namely flapping, stroke plane deviation and pitching, together with cambering and flexion. The decomposition is combined with aerodynamic simulations to investigate the cumulative effect of each motion on force production, and their primary contribution to the unsteady vortex dynamics. For the nearly straight and level flight of Hipposideros pratti , results show that the flapping motion by itself induced a moderate drag and lift. Stroke plane deviation increased lift, and nullified the drag. With the inclusion of the pitching motion into the kinematics, lift production further increased by a factor of more than 2.5, and exhibited a positive net thrust by virtue of the favorable wing orientation during the upstroke. The primary contribution of cambering, which included a maximum chord line displacement of ≈40% standard mean chord, was the stabilization of the leading edge vortex during the downstroke. This increased mean lift by about 35% at the expense of net thrust. Flexion was perhaps the most complex motion with maximum displacements of 75% standard mean chord. This was instrumental in reducing the negative lift during the upstroke by preventing the formation of strong leading edge vortices. The aerodynamic effective angle of attack emerged as a heuristic parameter to describe lift and net thrust production across movements.

show abstract

Variation of drag, lift and torque in a suspension of ellipsoidal particles

Cited by 32 publications

References 30 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

Bubble dynamics in bubbling fluidized beds of ellipsoidal particles

Canonical description of wing kinematics and dynamics for a straight flying insectivorous bat (Hipposideros pratti)

Contact Info

Product

Resources

About