Techno Press
You logged in as Techno Press

Coupled Systems Mechanics
  Volume 7, Number 4, August 2018, pages 407-420
DOI: http://dx.doi.org/10.12989/csm.2018.7.4.407
 


Hydrodynamic coupling distance between a falling sphere and downstream wall
Cheng-Chuan Lin, Hung-Tien Huang and Fu-Ling Yang

 
Abstract     [Full Text]
    In solid-liquid two phase flow, the knowledge of how descending solid particles affected by the presence of downstream wall is important. This work studies at what interstitial distance the velocity of a vertically descending sphere is affected by a downstream wall as a consequence of wall-modified hydrodynamic forces through a validated dynamic model. This interstitial distance-the hydrodynamic coupling distance Sc-is found to decay monotonically with the approach Stokes number St which compares the particle inertia to viscous drag characterized by the quasi-steady Stokes\' drag. The scaling relation Sc-St-1 decays monotonically as literature below the value of St equal to 10. However, the faster diminishing rate is found above the threshold value from St=10-40. Furthermore, an empirical relation of Sc-St shows dependence on the drop height which clearly indicates the non-negligible effect of unsteady hydrodynamic force components, namely the added mass force and the history force. Finally, we attempt a fitting relation which embedded the particle acceleration effect in the dependence of fitting constants on the diameter-scaled drop height.
 
Key Words
    hydrodynamic coupling; Stokes number; wall effect; added mass force; history force
 
Address
Cheng-Chuan Lin, Hung-Tien Huang and Fu-Ling Yang: Department of Mechanical Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan (R.O.C.)
 

Techno-Press: Publishers of international journals and conference proceedings.       Copyright © 2020 Techno Press
P.O. Box 33, Yuseong, Daejeon 305-600 Korea, Tel: +82-42-828-7996, Fax : +82-42-828-7997, Email: technop@chol.com