Turbulent flow characteristics and drag over 2-D forward-facing dune shaped structures with two different stoss-side slopes
Tóm tắt
The present paper explores the characteristics of turbulent flow and drag over two artificial 2-D forward-facing waveform structures with two different stoss side slopes of
$$50^{\circ }$$
and
$$90^{\circ },$$
respectively. Both structures possessed a common slanted lee side slope of
$$6^{\circ }.$$
Flume experiments were conducted at the Fluvial Mechanics Laboratory of Indian Statistical Institute, Kolkata. The velocity data were analyzed to identify the spatial changes in turbulent flow addressing the flow separation region with recirculating eddy, the Reynolds stresses, the turbulent events associated with burst-sweep cycles and the drag over two upstream-facing bedforms for Reynolds number
$$Re_h=1.44\times 10^5.$$
The divergence at the stoss side slope between the two structures revealed significant changes in the mean flow and turbulence. Comparison showed that during the flood-tide condition there was no flow separation region on the gentle lee side of the structure with smaller slope at the stoss side, while for the other structure with vertical stoss side slope a thick flow separation region with recirculating eddy was observed at the gentle lee side just downstream of the crest. The recirculating eddy induced on the lee-side had a strong influence on the resistance that the structure exerts to the flow due to loss of energy through turbulence. In contrast, a great amount of reduction in drag was observed in the case of smaller stoss side sloped structure as there was no flow separation. The quadrant analysis was also used to highlight the turbulent event evolution along the bed form structures under flood-tide conditions.
Tài liệu tham khảo
Addad YD, Laurence CT, Jacob MC (2003) Large eddy simulation of a forward–backward facing step for acoustic source identification. Int J Heat Fluid Flow 24:562–571
Agelinchaab M, Tachie M (2008) PIV study of separated and reattached open channel flow over surface mounted blocks. ASME J Fluids Eng 130(6):061206–061214
Ando T, Shakouchi T (2004) Flow characteristics over forward facing step and through abrupt contraction pipe and drag reduction. Res Rep Fac Eng Mie Univ 29:1–8
Armaly BF, Durst F, Pereira JCF, Schonung B (1983) Experimental and theoretical investigation of backward-facing step flow. J Fluid Mech 127:473–496
Ashley GM (1990) Classification of large-scale subaqueous bedforms: a new look at an old problem. J Sediment Petrol 60:160–172
Barkley D, Gomes M, Henderson R (2002) Three-dimensional instability in flow over a backward-facing step. J Fluid Mech 473:167–190
Bennett JP (1997) Resistance, sediment transport, and bedform geometry relationships in sandbed channels. In: Proceedings of the U.S. Geological Survey (USGS) sediment, workshop, 4–7 Feb
Bennett SJ, Best JL (1995) Mean flow and turbulence structure over fixed, two-dimensional dunes: implications for sediment transport and bedform stability. Sedimentology 42:491–513
Best J (2005) The fluid dynamics of river dunes: a review and some future research directions. J Geophys Res 110:F04S02. doi:10.1029/2004JF000218
Best J, Kostaschuk RA (2002) An experimental study of turbulent flow over a low-angle dune. J Geophys Res 107(C9):18(9)–18(19). doi:10.1029/2000JC000294
Camussi R, Felli M, Pereira F, Aloisio G, Marco AD (2008) Statistical properties of wall pressure fluctuations over a forward-facing step. Phys Fluids 20(7):075113
Casarsa L, Giannattasio P (2008) Three-dimensional features of the turbulent flow through a planar sudden expansion. Phys Fluids 20(1):015103
Cellino M, Graf WH (2000) Experiments on suspension flow in open channels with bed forms. J Hydraul Res 38(4):289–298
Dinehart RL (2002) Bedform movement recorded by sequential single-beam surveys in tidal rivers. J Hydrol 258:25–39
Eaton JK, Johnston JP (1981) A review of research on subsonic turbulent flow reattachment. AIAA J 19:1093–1100
Ernstsen VB, Noormets R, Winter C, Hebbeln D, Bartholoma A, Flemming BW, Bartholdy J (2006) Quantification of dune dynamics during a tidal cycle in an inlet channel of the Danish Wadden Sea. Geo-Mar Lett 26(3):151–163
Gabel SL (1993) Geometry and kinematics of dunes during steady and unsteady flows in the Calamus River, Nebraska, USA. Sedimentology 40(2):237–269
Goring DG, Nikora VI (2002) Despiking acoustic Doppler velocimeter data. J Hydraul Eng 128(1): 117–126
Jackson RG (1976) Sedimentological and fluid-dynamic implications of the turbulent bursting phenomenon in geophysical flows. J Fluid Mech 77:531–560
Julien PY, Klaassen GJ (1995) Sand-dune geometry of large river during floods. J Hydraul Eng 121(9):657–663
Kaftori D, Hetsroni G, Banerjee S (1998) The effect of particles on wall turbulence. Int J Multiphase Flow 24(3):359–386
Kiya M, Sasaki K (1983) Structure of a turbulent separation bubble. J Fluid Mech 137:83–113
Kostaschuk RA, Best JL (2005) The response of sand dunes to variations in tidal flow. J Geophys Res 110:F04S04. doi:10.1029/2004JF000176
Kostaschuk RA, Church MA (1993) Macroturbulence generated by dunes: Fraser River, Canada. Sediment Geol 85:25–37
Kostaschuk RA, Villard PV (1996) Flow and sediment transport over large subaqueous dunes: Fraser River, Canada. Sedimentology 43:849–863
Largeau J, Moriniere V (2007) Wall pressure fluctuatings and topology in separated flows over a forward-facing step. Exp Fluids 42(1):21–40
Le H, Moin P, Kim J (1997) Direct numerical simulation of turbulent flow over a backward-facing step. J Fluid Mech 330:349–374
Lefebvre A, Ernstsen VB, Winter C (2011) Influence of compound bedforms on hydraulic roughness in a tidal environment. Ocean Dyn 61(12):2201–2210
Lefebvre A, Ernstsen VB, Winter C (2013) Estimation of roughness lengths and flow separation over compound bedforms in a Natural Tidal inlet. Cont Shelf Res 61–62:98–111
Lefebvre A, Ferret Y, Paarlberg AJ, Ernstsen VB, Winter C (2013) Variation of flow separation over large bedforms during a tidal cycle. In: Marine and river dune dynamics MARID IV, Bruges, Belgium, 15 and 16 April, pp 169–175
Lu SS, Willmarth WW (1973) Measurements of the structure of the Reynolds stress in a turbulent boundary layer. J Fluid Mech 60:481–512
Lyn DA (1993) Turbulence measurements in open channel flows over artificial bed forms. J Hydraul Eng 119(3):306–326
Mao Y (2003) The effects of turbulent bursting on the sediment movement in suspension. Int J Sediment Res 18(2):148–157
Martinius AW, Gowland S (2010) Tide-influenced fluvial bedforms and tidal bore deposits (Late Jurassic Lourinha Formation, Lusitanian Basin, Western Portugal). Sedimentology. doi:10.1111/j.1365-3091.2010.01185.x
Mazumder BS, Ray RN, Dalal DC (2005) Size distributions of suspended particles in open channel flow over bed materials. Environmetrics 16(2):149–165
Mazumder BS, Pal DK, Ghoshal K, Ojha SP (2009) Turbulence statistics of flow over isolated scalene and isosceles triangular-shaped bedforms. J Hydraul Res 47(5):626–637
McLean SR, Wolfe SR, Nelson JM (1999) Spatially averaged flow over a wavy boundary revisited. J Geophys Res 104(C7):15743–15753
Mendoza C, Shen HW (1990) Investigation of turbulent flow over dunes. J Hydraul Eng 116(4):459–477
Nakagawa H, Nezu I (1981) Structure of space–time correlations of bursting phenomena in an open-channel flow. J Fluid Mech 104:1–43
Nezu I, Nakagawa H (1993a) Three-dimensional structures of coherent vortices generated behind dunes in turbulent free-surface flows. Refined flows modelling and turbulence measurements. In: Proceedings of the 5th international symposium, Paris, pp 603–612
Nezu I, Nakagawa H (1993b) Turbulence in open channel flows. IAHR monograph. Balkema, Rotterdam. ISBN 90-5410-118-0
Nezu I, Rodi W (1986) Open-channel measurements with a laser Doppler anemometer. J Hydraul Eng 112(5):335–355
Ojha SP, Mazumder BS (2008) Turbulence characteristics of flow region over a series of 2-D dune shaped structures. Adv Water Resour 31:561–576
Paarlberg AJ, Dohmen-Janssen CM, Hulscher SJMH, Termes P (2009) Modelling river dune evolution using a parameterization of flow separation. J Geophys Res 114:F01014
Pearson DS, Goulart PJ, Ganapathisubramani B (2011) Investigation of turbulent separation in a forward-facing step flow. In: 13th European turbulence conference. J Phys Conf Ser 318. doi:10.1088/1742-6596/318/2/022031
Poole RJ, Escudier MP (2003) Turbulent flow of a viscoelastic shear-thinning liquid through a plane sudden expansion of modest aspect ratio. J Non-Newton Fluid Mech 112:1–26
Ren H, Wu Y (2011) Turbulent boundary layers over smooth and rough forward-facing steps. Phys Fluids 23(4):1–17
Saleel CA, Shaija A, Jayaraj S (2011) Numerical simulation of fluid flow over a forward–backward facing step using immersed boundary method. Int J Eng Sci Technol 3(10):7714–7729
Sherry MJ, Jacono DL, Sheridan J (2010) An experimental investigation of the recirculation zone formed downstream of a forward facing step. J Wind Eng Ind Aerodyn 98:888–894
Singh AP, Paul AR, Ranjan P (2011) Investigation of reattachment length for a turbulent flow over a backward facing step for different step angle. Int J Eng Sci Technol 3(2):84–88
Smith JD, McLean SR (1977) Spatially averaged flow over a wavy surface. J Geophys Res 82(12): 1735–1746
Stuer H, Mass HG, Virant M, Becker J (1999) A volumetric 3D measurement tool for velocity field diagnostic in microgravity experiments. Meas Sci Technol 10:904–913
Toyama A, Shimizu Y, Yamaguchi S, Giri S (2007) Study of sediment transport rate over dune-covered beds. In: 5th IAHR symposium on river, coastal and estuarine morphodynamics. University of Twente, Enschede
Vanoni V, Hwang LS (1967) Relation between bed form and friction in streams. J Hydraul Div Am Soc Civ Eng 93(HY3):121–144
Venditti JG (2007) Turbulent flow and drag over fixed two- and three-dimensional dunes. J Geophys Res 112:F04008
Winter C, Ferret Y, Lefebvre Y, Ernstsen VB (2013) Geometric properties of hydraulically-relevant tidal bedforms. In: Marine and river dune dynamics MARID IV, Bruges, Belgium, 15 and 16 April, pp 337–338
Wu Y, Christensen KT (2006) Reynolds-stress enhancement associated with a short fetch of roughness in wall turbulence. AIAA J 44(12):3098–3106
Zarillo GA (1982) Stability of bedforms in a tidal environment. Mar Geol 48:337–351