DNS of turbulent drag reduction in a pressure-driven rod-roughened channel flow by microfiber additives

被引:6
作者
Moosaie, Amin [1 ]
机构
[1] Univ Yasuj, Dept Mech Engn, Turbulence Res Lab, Yasuj 75914353, Iran
关键词
Fiber suspension; Algebraic closure model; Direct numerical simulation; Turbulent drag reduction; Rod-roughened channel flow; NUMERICAL-SIMULATION; SURFACE-ROUGHNESS; FIBER ORIENTATION; ALGEBRAIC CLOSURE; SUSPENSIONS; STATISTICS; PARTICLES; STRESS; MODEL; LAYER;
D O I
10.1016/j.jnnfm.2016.02.010
中图分类号
O3 [力学];
学科分类号
08 ; 0801 ;
摘要
The turbulent drag reduction caused by microfiber additives in a pressure-driven rod-roughened channel flow at a nominal shear Reynolds number 395 is presented. Both channel walls are roughened by span wise rods of square cross section with a height of k(+) = 13.6 which translates to 1.7% of channel width. A pitch-to-height ratio of 8 is chosen. The effect of suspended fibers is modeled by an algebraic closure model, which allows the direct simulation of such complicated physics by significantly reducing the computational costs. Three simulations have been conducted; the Newtonian flow and the drag-reduced flows with two different fiber concentrations. As a result, 12.71% and 16.78% increase in the mean bulk velocities throughout the channel could be achieved for the two concentrations considered here. Also, the mean streamwise and wall-normal velocity profiles as well as Reynolds stresses at various locations between two consecutive roughness elements are presented and discussed. In the drag-reduced flow, the streamwise Reynolds normal stress is increased whereas the spanwise and wall-normal normal stresses are decreased. Also, the magnitude of the Reynolds shear stress is decreased in the fibrous flow. (C) 2016 Elsevier B.V. All rights reserved.
引用
收藏
页码:1 / 10
页数:10
相关论文
共 49 条
  • [1] THE USE OF TENSORS TO DESCRIBE AND PREDICT FIBER ORIENTATION IN SHORT FIBER COMPOSITES
    ADVANI, SG
    TUCKER, CL
    [J]. JOURNAL OF RHEOLOGY, 1987, 31 (08) : 751 - 784
  • [2] Torque-coupling and particle-turbulence interactions
    Andersson, Helge I.
    Zhao, Lihao
    Barri, Mustafa
    [J]. JOURNAL OF FLUID MECHANICS, 2012, 696 : 319 - 329
  • [3] Rheological properties of dilute suspensions of rigid and flexible fibers
    Andric, J.
    Lindstrom, S. B.
    Sasic, S.
    Nilsson, H.
    [J]. JOURNAL OF NON-NEWTONIAN FLUID MECHANICS, 2014, 212 : 36 - 46
  • [4] Turbulence structure in boundary layers over different types of surface roughness
    Antonia, R
    Krogstad, PÅ
    [J]. FLUID DYNAMICS RESEARCH, 2001, 28 (02) : 139 - 157
  • [5] The structure of turbulence in a rod-roughened channel
    Ashrafian, A
    Andersson, HI
    [J]. INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW, 2006, 27 (01) : 65 - 79
  • [6] DNS of turbulent flow in a rod-roughened channel
    Ashrafian, A
    Andersson, HI
    Manhart, M
    [J]. INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW, 2004, 25 (03) : 373 - 383
  • [7] Reynolds number effects in the outer layer of the turbulent flow in a channel with rough walls -: art. no. 065101
    Bakken, OM
    Krogstad, PÅ
    Ashrafian, A
    Andersson, HI
    [J]. PHYSICS OF FLUIDS, 2005, 17 (06) : 1 - 16
  • [8] BAKKEN OM, 2003, P 3 INT S TURB SHEAR, P105
  • [9] STRESS SYSTEM IN A SUSPENSION OF FORCE-FREE PARTICLES
    BATCHELOR, GK
    [J]. JOURNAL OF FLUID MECHANICS, 1970, 41 : 545 - +
  • [10] Comparison of theory and direct numerical simulations of drag reduction by rodlike polymers in turbulent channel flows
    Benzi, Roberto
    Ching, Emily S. C.
    De Angelis, Elisabetta
    Procaccia, Itamar
    [J]. PHYSICAL REVIEW E, 2008, 77 (04):