透水床面明渠湍流时空平均特征的大涡模拟与分析
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摘要
基于大涡模拟数据,研究了理想粗糙透水床面明渠湍流的时空平均特性.考虑到空间异构性,对比分析了不同位置的时空平均流速、雷诺剪应力、构造剪应力、脉动幅度的垂线分布.结果表明:第一,顶层床面之上,空间异构性的影响较小,不同位置的双平均流速符合类似的对数分布,但由于透水床面影响,卡门常数较不透水床面小;在床面附近,空间异构性影响较大,不同位置的双平均流速分别符合线性分布与多项式分布;在透水河床内部,靠近底层球孔的双平均流速为上部球孔双平均流速的1.55倍.第二,床面之上,雷诺剪应力占总剪应力的95%以上,占有主体地位;床面附近,紊动较大,构造剪应力不能忽略,其值大约占总剪应力的15%.由于流场的各向异性,纵向与垂向的脉动幅度有所差异.
This study focuses on the double-averaging(DA) turbulence characteristics of flow over an idealized permeable bed using the large-eddy simulation(LES). To discuss the spatial heterogeneity, the vertical distributions of DA velocity,DA Reynold shear stress(RSS), DA form-induced shear stress(FISS) and turbulence intensities in different positions are analyzed. It is shown that the spatial heterogeneity has a little influence in the upper flow region, and the distribution of DA velocity corresponds to the logarithmic law. The Von Karman constant obtained is significantly less than the normal value because of permeability. In the vicinity of bed, the spatial heterogeneity has a significant effect on the velocity distributions, which match with a polynomial series and a linear series respectively. Within the permeable bed, the peak velocity at lower pore is 1.55 times larger than that at upper pore. Above the crest bed level, the DA Reynolds shear stress is 95% of the total DA shear stress. The DA form-induced shear stress is 15% of the total DA shear stress occurring at the virtual bed level. The distributions of turbulence intensities in different positions show some discrepancies, which result from the spatial heterogeneity.
This study focuses on the double-averaging(DA) turbulence characteristics of flow over an idealized permeable bed using the large-eddy simulation(LES). To discuss the spatial heterogeneity, the vertical distributions of DA velocity,DA Reynold shear stress(RSS), DA form-induced shear stress(FISS) and turbulence intensities in different positions are analyzed. It is shown that the spatial heterogeneity has a little influence in the upper flow region, and the distribution of DA velocity corresponds to the logarithmic law. The Von Karman constant obtained is significantly less than the normal value because of permeability. In the vicinity of bed, the spatial heterogeneity has a significant effect on the velocity distributions, which match with a polynomial series and a linear series respectively. Within the permeable bed, the peak velocity at lower pore is 1.55 times larger than that at upper pore. Above the crest bed level, the DA Reynolds shear stress is 95% of the total DA shear stress. The DA form-induced shear stress is 15% of the total DA shear stress occurring at the virtual bed level. The distributions of turbulence intensities in different positions show some discrepancies, which result from the spatial heterogeneity.
引文
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2 Nikora V,Koll K,Mcewan I,et al.Velocity distribution in the roughness layer of rough-bed flows.Journal of Hydraulic EngineeringASCE,2004,130(10):1036-1042
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4 Aberle J.Measurements of armour layer roughness geometry function and porosity.Acta Geophysica,2007,55(1):23-32
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6 Mignot E,Hurther D,Barthelemy E.On the structure of shear stress and turbulent kinetic energy flux across the roughness layer of a gravel-bed channel flow.Journal of Fluid Mechanics,2009,638:423-452
7 Jimenez J.Turbulent flows over rough walls.Annual Review of Fluid Mechanics,2004,36:173-196
8 白静,方红卫,何国建.非淹没丁坝绕流的三维大涡模拟研究.力学学报,2013,45(2):151-157(Bai Jing,Fang Hongwei,He Guojian.Study of non-submerged groin turbulence flowin a shallowopen channel by LES.Chinese Journal of Theoretical and Applied Mechanics,2013,45(2):151-157(in Chinese))
9 Nikora VI,Smart GM.Turbulence characteristics of New Zealand gravel-bed rivers.Journal of Hydraulic Engineering-ASCE,1997,123(9):764-773
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11 Nikora VI,Rowinski PM.Rough-bed flows in geophysical,environmental,and engineering systems:Double-averaging approach and its applications-preface.Acta Geophysica,2008,56(3):529-533
12 Gimenez-Curto LA,Corniero MA.Flow characteristics in the interfacial shear layer between a fluid and a granular bed.Journal of Geophysical Research-Oceans,2002,107(C5):12-1–12-9
13 Nikora V,Mcewan I,Mclean S,et al.Double-Averaging concept for rough-bed open-channel and overland flows:Theoretical background.Journal of Hydraulic Engineering-ASCE,2007,133(8):873-883
14 Manes C,Pokrajac D,Mcewan I.Double-averaged open-channel flows with small relative submergence.Journal of Hydraulic Engineering-ASCE,2007,133(8):896-904
15 Nikora V,Goring D,Mcewan I,et al.Spatially averaged openchannel flow over rough bed.Journal of Hydraulic EngineeringASCE,2001,127(2):123-133
16 Germano M,Piomelli U,Moin P,et al.A dynamic subgrid-scale eddy viscosity model.Physics of Fluids A-Fluid Dynamics,1991,3(7):1760-1765
17 Bomminayuni S,Stoesser T.Turbulence statistics in an openchannel flow over a rough bed.Journal of Hydraulic EngineeringASCE,2011,137(11):1347-1358
18 Dasgupta A,Paudyal GN.Characteristics of free-surface flow over gravel bed.Journal of Irrigation and Drainage Engineering-ASCE,1985,111(4):299-318
19 陈兴伟,林木生,程年生等.粗糙透水床面明渠水流的垂线流速分布.水科学进展,2013,24(6):849-854(Chen Xingwei,Lin Musheng1,Cheng Niansheng,et al.Velocity profile of turbulent open-channel flows over rough and permeable beds.Advances in Water Science,2013,24(6):849-854(in Chinese))
20 Nezu I,Kadota A,Nakagawa H.Turbulent structure in unsteady depth-varying open-channel flows.Journal of Hydraulic Engineering-ASCE,1997,123(9):752-763
21 Manes C,Pokrajac D,Nikora VI,et al.Turbulent friction in flows over permeable walls.Geophysical Research Letters,2011,38:L03402
22 Manes C,Pokrajac D,Mcewan I,et al.Turbulence structure of open channel flows over permeable and impermeable beds:A comparative study.Physics of Fluids,2009,21:12510912
23 Nezu I,Nakagawa H.Turbulence in Open-Channel Flows.Balkema,Rotterdam,Netherlands.1993
2 Nikora V,Koll K,Mcewan I,et al.Velocity distribution in the roughness layer of rough-bed flows.Journal of Hydraulic EngineeringASCE,2004,130(10):1036-1042
3 Coleman SE,Nikora VI,Mclean SR,et al.Subelement formdrag parameterization in rough-bed flows.Journal of Hydraulic Engineering-ASCE,2007,133(2):121-129
4 Aberle J.Measurements of armour layer roughness geometry function and porosity.Acta Geophysica,2007,55(1):23-32
5 Dey S,Das R.Gravel-Bed hydrodynamics:Double-averaging approach.Journal of Hydraulic Engineering-ASCE,2012,138(8):707-725
6 Mignot E,Hurther D,Barthelemy E.On the structure of shear stress and turbulent kinetic energy flux across the roughness layer of a gravel-bed channel flow.Journal of Fluid Mechanics,2009,638:423-452
7 Jimenez J.Turbulent flows over rough walls.Annual Review of Fluid Mechanics,2004,36:173-196
8 白静,方红卫,何国建.非淹没丁坝绕流的三维大涡模拟研究.力学学报,2013,45(2):151-157(Bai Jing,Fang Hongwei,He Guojian.Study of non-submerged groin turbulence flowin a shallowopen channel by LES.Chinese Journal of Theoretical and Applied Mechanics,2013,45(2):151-157(in Chinese))
9 Nikora VI,Smart GM.Turbulence characteristics of New Zealand gravel-bed rivers.Journal of Hydraulic Engineering-ASCE,1997,123(9):764-773
10 Kironoto BA,Graf WH.Turbulence characteristics in rough uniform open-channel flow.Proceedings of the Institution of Civil Engineers-Water Maritime and Energy,1994,106(4):333-344
11 Nikora VI,Rowinski PM.Rough-bed flows in geophysical,environmental,and engineering systems:Double-averaging approach and its applications-preface.Acta Geophysica,2008,56(3):529-533
12 Gimenez-Curto LA,Corniero MA.Flow characteristics in the interfacial shear layer between a fluid and a granular bed.Journal of Geophysical Research-Oceans,2002,107(C5):12-1–12-9
13 Nikora V,Mcewan I,Mclean S,et al.Double-Averaging concept for rough-bed open-channel and overland flows:Theoretical background.Journal of Hydraulic Engineering-ASCE,2007,133(8):873-883
14 Manes C,Pokrajac D,Mcewan I.Double-averaged open-channel flows with small relative submergence.Journal of Hydraulic Engineering-ASCE,2007,133(8):896-904
15 Nikora V,Goring D,Mcewan I,et al.Spatially averaged openchannel flow over rough bed.Journal of Hydraulic EngineeringASCE,2001,127(2):123-133
16 Germano M,Piomelli U,Moin P,et al.A dynamic subgrid-scale eddy viscosity model.Physics of Fluids A-Fluid Dynamics,1991,3(7):1760-1765
17 Bomminayuni S,Stoesser T.Turbulence statistics in an openchannel flow over a rough bed.Journal of Hydraulic EngineeringASCE,2011,137(11):1347-1358
18 Dasgupta A,Paudyal GN.Characteristics of free-surface flow over gravel bed.Journal of Irrigation and Drainage Engineering-ASCE,1985,111(4):299-318
19 陈兴伟,林木生,程年生等.粗糙透水床面明渠水流的垂线流速分布.水科学进展,2013,24(6):849-854(Chen Xingwei,Lin Musheng1,Cheng Niansheng,et al.Velocity profile of turbulent open-channel flows over rough and permeable beds.Advances in Water Science,2013,24(6):849-854(in Chinese))
20 Nezu I,Kadota A,Nakagawa H.Turbulent structure in unsteady depth-varying open-channel flows.Journal of Hydraulic Engineering-ASCE,1997,123(9):752-763
21 Manes C,Pokrajac D,Nikora VI,et al.Turbulent friction in flows over permeable walls.Geophysical Research Letters,2011,38:L03402
22 Manes C,Pokrajac D,Mcewan I,et al.Turbulence structure of open channel flows over permeable and impermeable beds:A comparative study.Physics of Fluids,2009,21:12510912
23 Nezu I,Nakagawa H.Turbulence in Open-Channel Flows.Balkema,Rotterdam,Netherlands.1993