Please use this identifier to cite or link to this item: http://lib.jncasr.ac.in:8080/jspui/handle/10572/1861
Title: On Knudsen-minimum effect and temperature bimodality in a dilute granular Poiseuille flow
Authors: Alam, Meheboob
Mahajan, Achal
Shivanna, Deepthi
Keywords: Mechanics
Fluids & Plasmas Physics
granular media
molecular dynamics
rarefied gas flow
Density Waves
Gas
Equations
Stress
Issue Date: 2015
Publisher: Cambridge University Press
Citation: Journal of Fluid Mechanics
782
Alam, M.; Mahajan, A.; Shivanna, D., On Knudsen-minimum effect and temperature bimodality in a dilute granular Poiseuille flow. Journal of Fluid Mechanics 2015, 782, 99-126.
Abstract: The numerical simulation of gravity-driven flow of smooth inelastic hard disks through a channel, dubbed 'granular' Poiseuille flow, is conducted using event-driven techniques. We find that the variation of the mass-flow rate (Q) with Knudsen number (Kn) can be non-monotonic in the elastic limit (i.e. the restitution coefficient e(n) -> 1) in channels with very smooth walls. The Knudsen-minimum effect (i.e. the minimum flow rate occurring at Kn similar to 0(1) for the Poiseuille flow of a molecular gas) is found to be absent in a granular gas with e(n) < 0.99, irrespective of the value of the wall roughness. Another rarefaction phenomenon, the bimodality of the temperature profile, with a local minimum (T-min) at the channel centerline and two symmetric maxima (T-max) away from the centerline, is also studied. We show that the inelastic dissipation is responsible for the onset of temperature bimodality (i.e. the 'excess' temperature, Delta T = (T-max/T-min - 1) not equal 0) near the continuum limit (Kn similar to 0), but the rarefaction being its origin (as in the molecular gas) holds beyond Kn similar to O(0.1). The dependence of the excess temperature Delta T on the restitution coefficient is compared with the predictions of a kinetic model, with reasonable agreement in the appropriate limit. The competition between dissipation and rarefaction seems to be responsible for the observed dependence of both the mass-flow rate and the temperature bimodality on Kn and e(n) in this flow. The validity of the Navier-Stokes-order hydrodynamics for granular Poiseuille flow is discussed with reference to the prediction of bimodal temperature profiles and related surrogates.
Description: Restricted access
URI: http://hdl.handle.net/10572/1861
ISSN: 0022-1120
Appears in Collections:Research Articles (Meheboob Alam)

Files in This Item:
File Description SizeFormat 
1517_On Knudsen-minimum-effect.pdf
  Restricted Access
1.37 MBAdobe PDFView/Open Request a copy


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.