Study the Effect of Roughness on the Higher Order Moment to Extract Information about the Turbulent Flow Structure in an Open Channel Flow

Authors: Md Abdullah Al Faruque, Ram Balachandar

Abstract:

The present study was carried out to understand the extent of effect of roughness and Reynolds number in open channel flow (OCF). To this extent, four different types of bed surface conditions consisting smooth, distributed roughness, continuous roughness, natural sand bed and two different Reynolds number for each bed surfaces were adopted in this study. Particular attention was given on mean velocity, turbulence intensity, Reynolds shear stress, correlation, higher order moments and quadrant analysis. Further, the extent of influence of roughness and Reynolds number in the depth-wise direction also studied. Increasing Reynolds shear stress near rough beds are noticed due to arrays of discrete roughness elements and flow over these elements generating a series of wakes which contributes to the generation of significantly higher Reynolds shear stress.

Keywords: Bed roughness, ejection, sweep, open channel flow, Reynolds Shear Stress, turbulent boundary layer, velocity triple product.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1123961

References:

[1] Rashidi, M., Hetsroni, G., and Banerjee, S. (1990). “Particle-turbulence interaction in a boundary layer.” International Journal of Multiphase Flow, 16(6), 935-949.
[2] Grass, A. J. (1971) “Structural features of turbulent flow over smooth and rough boundaries.” Journal of Fluid Mechanics, 50(2), 233-255.
[3] Nakagawa, H. and Nezu, I. (1977). “Prediction of the contributions to the Reynolds stress from bursting events in open-channel flows.” Journal of Fluid Mechanics, 80(1), 99-128.
[4] Nezu, I. and Nakagawa, H. (1993). Turbulence in open-channel flows. IAHR Monograph, A. A. Balkema, The Netherlands.
[5] Tachie, M. F. (2001). “Open-channel turbulent boundary layers and wall jets on rough surfaces.” PhD thesis, University of Saskatchewan, Saskatchewan, Canada.
[6] Nezu, I. (2005). “Open-channel flow turbulence and its research prospect in the 21st century.” Journal of Hydraulic Engineering, 131(4), 229-246.
[7] Balachandar, R., and Bhuiyan, F. (2007). “Higher-order moments of velocity fluctuations in an open channel flow with large bottom roughness.” Journal of Hydraulic Engineering, 133(1), 77-87.
[8] Afzal, B., Faruque, M. A. A., and Balachandar, R. (2009). “Effect of Reynolds number, near-wall perturbation and turbulence on smooth open channel flows.” Journal of Hydraulic Research, 47(1), 66-81.
[9] Patel V. C. (1998). “Perspective: Flow at high Reynolds number and over rough surfaces – Achilles heel of CFD.” Journal of Fluids Engineering, 120(3), 434-444.
[10] Roussinova, V., Biswas, N., and Balachandar, R. (2008). “Revisiting turbulence in smooth uniform open channel flow.” Journal of Hydraulic Research, 46(Suppl. 1), 36-48.
[11] Kirkgöz, M. S., and Ardiçhoğlu, M. (1997). “Velocity profiles of developing and developed open channel flow.” Journal of Hydraulic Engineering, 123(2), 1099-1105.
[12] Tachie, M. F., Bergstrom, D. J., and Balachandar, R. (2003). “Roughness effects in low-Re open-channel turbulent boundary layers.” Experiments in Fluids, 35, 338-346.
[13] Balachandar, R., and Patel, V. C. (2002). “Rough wall boundary layer on plates in open channels.” Journal of Hydraulic Engineering, 128(10), 947-951.
[14] Tachie, M. F., Bergstrom, D. J., and Balachandar, R. (2000). “Rough wall turbulent boundary layers in shallow open channel flow.” Journal of Fluids Engineering, 122, 533-541.
[15] Kaftori, D., Hetsroni, G., and Banerjee, S. (1995). “Particle behavior in the turbulent boundary layer. I. Motion, deposition, and entrainment.” Physics of Fluids, 7(5), 1095-1106.
[16] Dancey, C. L., Balakrishnan, M., Diplas, P., and Papanicolaou, A. N. (2000). “The spatial inhomogeneity of turbulence above a fully rough, packed bed in open channel flow.” Experiments in Fluids, 29(4), 402-410.
[17] Tachie, M. F., Bergstrom, D. J., and Balachandar, R. (2004). “Roughness effects on the mixing properties in open channel turbulent boundary layers.” Journal of Fluids Engineering, 126, 1025-1032.
[18] Bigillon, F., Niňo, Y., and Garcia, M. H. (2006). “Measurements of turbulence characteristics in an open-channel flow over a transitionally-rough bed using particle image velocimetry.” Experiments in Fluids, 41(6), 857-867.
[19] Dancey, C. L., Balakrishnan, M., Diplas, P., and Papanicolaou, A. N. (2000). “The spatial inhomogeneity of turbulence above a fully rough, packed bed in open channel flow.” Experiments in Fluids, 29(4), 402-410.
[20] Faruque, M. A. A. (2009). “Smooth and rough wall open channel flow including effects of seepage and ice cover.” PhD thesis, University of Windsor, Windsor, ON, Canada.
[21] Schlichting, H. (1979). Boundary-Layer theory. McGraw-Hill Classic Textbook Reissue Series, McGraw-Hill, Inc., United States of America.
[22] Faruque, M. A. A., Sarathi, P., and Balachandar, R. (2006). “Clear water local scour by submerged three-dimensional wall jets: Effect of tailwater depth.” Journal of Hydraulic Engineering, 132(6), 575-580.
[23] Bey, A., Faruque, M. A. A., and Balachandar, R. (2007). “Two dimensional scour hole problem: Role of fluid structures.” Journal of Hydraulic Engineering, 133(4), 414-430.
[24] Krogstad, P.-A., Andersson, H. I., Bakken, O. M., and Ashrafian, A. (2005). “An experimental and numerical study of channel flow with rough walls.” Journal of Fluid Mechanics, 530, 327-352.
[25] Agelinchaab, M., and Tachie, M. F. (2006). “Open channel turbulent flow over hemispherical ribs.” International Journal of Heat and Fluid Flow, 27(6), 1010-1027.
[26] Schultz, M. P. and Flack, K. A. (2007). “The rough-wall turbulent boundary layer from the hydraulically smooth to the fully rough regime.” Journal of Fluid Mechanics, 580, 381-405.
[27] Flack, K. A., Schultz, M. P. and Shapiro, T. A. (2005). “Experimental support for Townsend’s Reynolds number similarity hypothesis on rough walls.” Physics of Fluids, 17(3), 35102-1-9.
[28] Antonia, R. A., and Krogstad, P-A. (2001). “Turbulence structure in boundary layers over different types of surface roughness.” Fluid Dynamics Research, 28(2), 139-157.