Similarity of the streamwise velocity component in very-rough-wall channel flow

被引:19
作者
Birch, David M. [1 ]
Morrison, Jonathan F. [1 ]
机构
[1] Univ London Imperial Coll Sci Technol & Med, Dept Aeronaut, London SW7 2AZ, England
基金
英国工程与自然科学研究理事会; 加拿大自然科学与工程研究理事会;
关键词
pipe flow boundary layer; turbulent boundary layers; TURBULENT-BOUNDARY-LAYER; PIPE; SMOOTH; HYPOTHESIS; FRICTION;
D O I
10.1017/S0022112010004647
中图分类号
O3 [力学];
学科分类号
08 ; 0801 ;
摘要
The streamwise velocity component is studied in fully developed turbulent channel flow for two very rough surfaces and a smooth surface at comparable Reynolds numbers. One rough surface comprises sparse and isotropic grit with a highly non-Gaussian distribution. The other is a uniform mesh consisting of twisted rectangular elements which form a diamond pattern. The mean roughness heights (+/- the standard deviation) are, respectively, about 76(+/- 42) and 145(+/- 150) wall units. The flow is shown to be two-dimensional and fully developed up to the fourth-order moment of velocity. The mean velocity profile over the grit surface exhibits self-similarity (in the form of a logarithmic law) within the limited range of 0.04 <= y/h <= 0.06, but the profile over the mesh surface does not, even though the mean velocity deficit and higher moments (up to the fourth order) all exhibit outer scaling over both surfaces. The distinction between self-similarity and outer similarity is clarified and the importance of the former is explained. The wake strength is shown to increase slightly over the grit surface but decrease over the mesh surface. The latter result is contrary to recent measurements in rough-wall boundary layers. Single- and two-point velocity correlations reveal the presence of large-scale streamwise structures with circulation in the plane orthogonal to the mean velocity. Spanwise correlation length scales are significantly larger than corresponding ones for both internal and external smooth-wall flows.
引用
收藏
页码:174 / 201
页数:28
相关论文
共 46 条
[1]   Turbulence structure in boundary layers over different types of surface roughness [J].
Antonia, R ;
Krogstad, PÅ .
FLUID DYNAMICS RESEARCH, 2001, 28 (02) :139-157
[2]   Reynolds number effects in the outer layer of the turbulent flow in a channel with rough walls -: art. no. 065101 [J].
Bakken, OM ;
Krogstad, PÅ ;
Ashrafian, A ;
Andersson, HI .
PHYSICS OF FLUIDS, 2005, 17 (06) :1-16
[3]   Effect of roughness on wall-bounded turbulence [J].
Bhaganagar, K ;
Kim, J ;
Coleman, G .
FLOW TURBULENCE AND COMBUSTION, 2004, 72 (2-4) :463-492
[4]  
BIRCH D, 2010, J IND AERO WIN UNPUB
[5]   INACTIVE MOTION AND PRESSURE FLUCTUATIONS IN TURBULENT BOUNDARY LAYERS [J].
BRADSHAW, P .
JOURNAL OF FLUID MECHANICS, 1967, 30 :241-&
[6]  
BREUER KS, 1995, EXP FLUIDS, V19, P138, DOI 10.1007/BF00193861
[7]   Rough-wall boundary layers: mean flow universality [J].
Castro, Ian P. .
JOURNAL OF FLUID MECHANICS, 2007, 585 :469-485
[8]  
Clauser F., 1956, Advances in Applied Mechanics, V4, P1, DOI [DOI 10.1016/S0065-2156(08)70370-3, 10.1016/S0065-2156(08)70370-3]
[9]   Experiments with fluid friction in roughened pipes [J].
Colebrook, CF ;
White, CM .
PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON SERIES A-MATHEMATICAL AND PHYSICAL SCIENCES, 1937, 161 (A906) :367-381
[10]   Velocity-defect scaling for turbulent boundary layers with a range of relative roughness [J].
Connelly, JS ;
Schultz, MP ;
Flack, KA .
EXPERIMENTS IN FLUIDS, 2006, 40 (02) :188-195