Skip to main content
    • Aa
    • Aa

Force and torque acting on particles in a transitionally rough open-channel flow

  • Clemens Chan-Braun (a1), Manuel García-Villalba (a1) and Markus Uhlmann (a1)

Direct numerical simulation of open channel flow over a geometrically rough wall has been performed at a bulk Reynolds number of . The wall consisted of a layer of spheres in a square arrangement. Two cases have been considered. In the first case the spheres are small (with diameter equivalent to wall units) and the limit of the hydraulically smooth flow regime is approached. In the second case the spheres are more than three times larger ( wall units) and the flow is in the transitionally rough flow regime. Special emphasis is given to the characterisation of the force and torque acting on a particle due to the turbulent flow. It is found that in both cases the mean drag, lift and spanwise torque are to a large extent produced at the top region of the particle surface. The intensity of the particle force fluctuations is significantly larger in the large-sphere case, while the trend differs for the fluctuations of the individual components of the torque. A simplified model is used to show that the torque fluctuations might be explained by the spheres acting as a filter with respect to the size of the flow scales which can effectively generate torque fluctuations. Fluctuations of both force and torque are found to exhibit strongly non-Gaussian probability density functions with particularly long tails, an effect which is more pronounced in the small-sphere case. Some implications of the present results for sediment erosion are briefly discussed.

Corresponding author
Email address for correspondence:
Linked references
Hide All

This list contains references from the content that can be linked to their source. For a full set of references and notes please see the PDF or HTML where available.

4. P. Bagchi & S. Balachandar 2003 Effect of turbulence on the drag and lift of a particle. Phys. Fluids 15 (11), 34963513.

7. P. Bradshaw 2000 A note on ‘critical roughness height’ and ‘transitional roughness’. Phys. Fluids 12 (6), 16111614.

9. C. F. Colebrook 1939 Turbulent flow in pipes with particular reference to the transition region between the smooth- and rough-pipe laws. J. Inst. Civil Engrs 11, 133156.

13. H. A. Einstein & E.-S. A. El-Samni 1949 Hydrodynamic forces on a rough wall. Rev. Mod. Phys. 21 (3), 520524.

14. E. A. Fadlun , R. Verzicco , P. Orlandi & J. Mohd-Yusof 2000 Combined immersed-boundary finite-difference methods for three-dimensional complex flow simulations. J. Comput. Phys. 161 (1), 3560.

17. M. H. García 2008 Sedimentation Engineering: Processes, Measurements, Modeling, and Practice. American Soc. Civil Eng. (ASCE), ASCE Manual of Practice 110.

21. B. Hofland & J. Battjes 2006 Probability density functions of instantaneous drag forces and shear stresses on a bed. J. Hydraul. Engng 132 (11), 11691175.

22. B. Hofland , J. Battjes & R. Booij 2005 Measurement of fluctuating pressures on coarse bed material. J. Hydraul. Engng 131 (9), 770781.

30. G. P. Krishnan & D. T. J. Leighton 1995 Inertial lift on a moving sphere in contact with a plane wall in a shear flow. Phys. Fluids 7 (11), 25382545.

38. C. Manes , D. Pokrajac & I. McEwan 2007 Double-averaged open-channel flows with small relative submergence. J. Hydraul. Engng 133 (8), 896904.

39. C. Manes , D. Pokrajac , V. I. Nikora , L. Ridolfi & D. Poggi 2011 Turbulent friction in flows over permeable walls. Geophys. Res. Lett. 38 (3), L03402.

40. I. Marusic , B. J. McKeon , P. A. Monkewitz , H. M. Nagib , A. J. Smits & K. R. Sreenivasan 2010 Wall-bounded turbulent flows at high Reynolds numbers: recent advances and key issues. Phys. Fluids 22 (6), 065103.

46. V. Nikora , I. McEwan , S. McLean , S. Coleman , D. Pokrajac & R. Walters 2007 Double-averaging concept for rough-bed open-channel and overland flows: theoretical background. J. Hydraul. Engng 133 (8), 873883.

47. V. I. Nikora , D. G. Goring , I. MacEwan & G. Griffiths 2001 Spatially averaged open-channel flow over rough bed. J. Hydraul. Engng 127 (2), 123133.

57. D. Pokrajac & C. Manes 2009 Velocity measurements of a free-surface turbulent flow penetrating a porous medium composed of uniform-size spheres. Trans. Porous Med. 78, 367383.

59. M. R. Raupach , R. A. Antonia & S. Rajagopalan 1991 Rough-wall turbulent boundary layers. Appl. Mech. Rev. 44 (1), 125.

68. A. S. Thom 1971 Momentum absorption by vegetation. Q. J. R. Meteorol. Soc. 97 (414), 414428.

75. M. Uhlmann 2008 Interface-resolved direct numerical simulation of vertical particulate channel flow in the turbulent regime. Phys. Fluids 20 (5), 053305.

80. L. Zeng , F. Najjar , S. Balachandar & P. Fischer 2009 Forces on a finite-sized particle located close to a wall in a linear shear flow. Phys. Fluids 21 (3), 033302.

Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Journal of Fluid Mechanics
  • ISSN: 0022-1120
  • EISSN: 1469-7645
  • URL: /core/journals/journal-of-fluid-mechanics
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Altmetric attention score

Full text views

Total number of HTML views: 0
Total number of PDF views: 79 *
Loading metrics...

Abstract views

Total abstract views: 164 *
Loading metrics...

* Views captured on Cambridge Core between September 2016 - 23rd September 2017. This data will be updated every 24 hours.