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Reduced particle se...
Reduced particle settling speed in turbulence
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- Fornari, Walter (författare)
- KTH,Mekanik,Linné Flow Center, FLOW,SeRC - Swedish e-Science Research Centre
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Picano, Francesco (författare)
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- Sardina, Gaetano (författare)
- KTH,Mekanik,Linné Flow Center, FLOW,SeRC - Swedish e-Science Research Centre
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- Brandt, Luca (författare)
- KTH,Mekanik,Linné Flow Center, FLOW,SeRC - Swedish e-Science Research Centre
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(creator_code:org_t)
- 2016-10-27
- 2016
- Engelska.
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Ingår i: Journal of Fluid Mechanics. - : Cambridge University Press. - 0022-1120 .- 1469-7645. ; 808, s. 153-167
- Relaterad länk:
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http://arxiv.org/pdf...
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- We study the settling of finite-size rigid spheres in sustained homogeneous isotropic turbulence (1111) by direct numerical simulations using an immersed boundary method to account for the dispersed solid phase. We study semi-dilute suspensions at different Galileo numbers, Ga. The Galileo number is the ratio between buoyancy and viscous forces, and is here varied via the solid-to-fluid density ratio rho(p)/rho(f), The focus is on particles that are slightly heavier than the fluid. We find that in HIT, the mean settling speed is less than that in quiescent fluid; in particular, it reduces by 6 %-60 % with respect to the terminal velocity of an isolated sphere in quiescent fluid as the ratio between the latter and the turbulent velocity fluctuations it is decreased. Analysing the fluid particle relative motion, we find that the mean settling speed is progressively reduced while reducing rho(p)/rho(f) due to the increase of the vertical drag induced by the particle cross-flow velocity. Unsteady effects contribute to the mean overall drag by about 6%-10%. The probability density functions of particle velocities and accelerations reveal that these are closely related to the features of the turbulent flow. The particle mean-square displacement in the settling direction is found to be similar for all Ga if time is scaled by (2a)/u' (where 2a is the particle diameter and a is the turbulence velocity root mean square).
Ämnesord
- TEKNIK OCH TEKNOLOGIER -- Maskinteknik -- Teknisk mekanik (hsv//swe)
- ENGINEERING AND TECHNOLOGY -- Mechanical Engineering -- Applied Mechanics (hsv//eng)
Nyckelord
- multiphase and particle-laden flows
- particle/fluid flow
- suspensions
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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