Abstract
The turbulent flow characteristics in the vicinity of mid-channel bar are studied in this paper. The velocity is measured with the help of the acoustic Doppler velocimetry (ADV). Fractal modelling is done for analysing the fractal nature of bursting events. The conditional Reynolds stress structure was analysed by using the quadrant technique. Decomposition of Reynolds stress help in studying the distribution of stress among the four quadrants. The hole-size concept is utilized for segregating the extreme bursting events from the low intensity events. Variation of quadrants stresses with the hole-size is analysed. The result of hole-size study indicates that the extreme turbulent burst is produced by the mid channel bar. The new parameter inclination ratio is evolved in this research to reflect streambed elevation changes. The results indicate that the high-level turbulence is generated at region near upstream end of mid-channel bar. The presence of mid-channel bar causes the critical changes to the turbulent structure of flow, where high Reynolds stresses are generated at region near upstream region of mid-channel bar. Third order moments are computed for vertical lines in the proximity of mid-channel bar. High value of third order moments for bar condition indicate that the intense turbulent mixing and momentum exchange take place.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Ashmore, P. E. (1982). “Laboratory modelling of gravel braided stream morphology.” Earth Surface Processes and Landforms, Vol. 7, No. 3, pp. 201–225, DOI: https://doi.org/10.1002/esp.3290070301.
Ashmore, P. (1991). “Channel morphology and bed load pulses in braided, gravel-bed streams.” Geografiska Annaler: Series A, Physical Geography, Vol 73, No. 1, pp. 37–52, DOI: https://doi.org/10.2307/521212.
Ashmore, P. and Parker, G. (1983). “Confluence scour in coarse braided streams.” Water Resources Research, Vol. 19, No. 2, pp. 392–402, DOI: https://doi.org/10.1029/WR019i002p00392.
Ashworth, P. J. (1996). “Mid-channel bar growth and its relationship to local flow strength and direction.” Earth Surface Processes and Landforms, Vol. 21, No. 2, pp. 103–123, DOI: https://doi.org/10.1002/(SICI)1096-9837(199602)21:2<103::AID-ESP569>3.0.CO;2-O.
Cea, L., Puertas, J., and Pena, L. (2007). “Velocity measurements on highly turbulent free surface flow using ADV.” Experiments in Fluids, Vol. 42, No. 3, pp. 333–348, DOI: https://doi.org/10.1007/s00348-006-0237-3.
Coceal, O., Dobre, A., Thomas, T. G., and Belcher, S. E. (2007). “Structure of turbulent flow over regular arrays of cubical roughness.” J. Fluid Mech., Vol. 589, pp. 375–409, DOI: https://doi.org/10.1017/S002211200700794X.
Ferguson, R. (1993). “Understanding braiding processes in gravel-bed rivers: Progress and unsolved problems.” Geological Society, London, Special Publications, Vol. 75, No. 1, pp. 74–87, DOI: https://doi.org/10.1144/GSL.SP.1993.075.01.03.
Gad-el-Hak, M. and Bandyopadhyay, P. R. (1994). “Reynolds number effects in wall-bounded turbulent flows.” Appl. Mech. Rev., Vol. 47, No. 8, pp. 307–365, DOI: https://doi.org/10.1115/1.3111083.
Gheisi, A. R., Alavimoghaddam, M. R., and Dadrasmoghaddam, A. (2006). “Markovian-Octant analysis based stable turbulent shear stresses in near-bed bursting phenomena of vortex settling chamber.” Environmental Fluid Mechanics, Vol. 6, No. 6, pp. 549–572, DOI: https://doi.org/10.1007/s10652-006-9009-0.
Keshavarzi, A. and Shirvani, A. (2002). “Probability analysis of instantaneous shear stress and entrained particles from the bed.” Proceedings of the CSCE/EWRI of ASCE Environmental Engineering, Niagara Falls, ON, Canada.
Khan, M. D. and Sharma, N. (2018). “Analysis of turbulent flow characteristics around bar using the conditional bursting technique for varying discharge conditions.” KSCE Journal of Civil Engineering, Vol. 22, No. 7, pp. 2315–2324, DOI: https://doi.org/10.1007/s12205-017-0018-y.
Kleinhans, M. G. and van den Berg, J. H. (2011). “River channel and bar patterns explained and predicted by an empirical and a physics-based method.” Earth Surface Processes and Landforms, Vol. 36, No. 6, pp. 721–738, DOI: https://doi.org/10.1002/esp.2090.
Leopold, L. and Wolman, M. (1957). “River channel patterns.” Fluv Geom: Geom. Crit. Conc., Vol. 3, No. 3, pp. 347–354.
Mianaei, S. J. and Keshavarzi, A. R. (2008). “Spatio-temporal variation of transition probability of bursting events over the ripples at the bed of open channel.” Stochastic Environmental Research and Risk Assessment, Vol. 22, No. 2, pp. 257–264, DOI: https://doi.org/10.1007/s00477-007-0114-5.
Nelson, J. M., Shreve, R. L., McLean, S. R., and Drake, T. G. (1995). “Role of near-bed turbulence structure in bed load transport and bed form mechanics.” Water Resources Research, Vol. 31, No. 8, pp. 2071–2086, DOI: https://doi.org/10.1029/95WR00976.
Nikora, V. and Goring, D. (2000). “Flow turbulence over fixed and weakly mobile gravel beds.” Journal of Hydraulic Engineering, Vol. 126, No. 9, pp. 679–690, DOI: https://doi.org/10.1061/(ASCE)0733-9429(2000)126:9(679).
Saha, P., Biswas, G., Mandal, A. C., and Sarkar, S. (2017). “Investigation of coherent structures in a turbulent channel with built-in longitudinal vortex generators.” International Journal of Heat and Mass Transfer, Vol. 104, pp. 178–198, DOI: https://doi.org/10.1016/j.ijheatmasstransfer.2016.07.105.
Sapozhnikov, V. and Foufoula-Georgiou, E. (1996). “Self-affinity in braided rivers.” Water Resources Research, Vol. 32, No. 5, pp. 1429–1439, DOI: https://doi.org/10.1029/96WR00490.
Schmeeckle, M. (2015). “The role of velocity, pressure, and bed stress fluctuations in bed load transport over bed forms: Numerical simulation downstream of a backward-facing step.” Earth Surface Dynamics, Vol. 3, No. 1, p. 105, DOI: https://doi.org/10.5194/esurf-3-105-2015.
Schumm, S. and Khan, H. (1972). “Experimental study of channel patterns.” Geological Society of America Bulletin, Vol. 83, No. 6, pp. 1755–1770, DOI: https://doi.org/10.1130/0016-7606(1972)83[1755:ESOCP]2.0. CO;2.
Scotti, A. and Meneveau, C. (1999). “A fractal model for large eddy simulation of turbulent flow.” Physica D: Nonlinear Phenomena, Vol. 127, No. 3, pp. 198–232, DOI: https://doi.org/10.1016/S0167-2789(98)00266-8.
Sharma, N. (2004). Mathematical modelling and braid indicators, The Brahmaputra basin water resources, Springer, Dordrecht, Netherlands, pp. 229–260, DOI: https://doi.org/10.1007/978-94-017-0540-0_11.
Smith, N. (1970). “The braided stream depositional environment: comparison of the Platte River with some Silurian clastic rocks, north-central Appalachians.” Geological Society of America Bulletin, Vol. 81, No. 10, pp. 2993–3014, DOI: https://doi.org/10.1130/0016-7606(1970)81[2993:TBSDEC]2.0.CO;2.
Strom, K. B. and Papanicolaou A. N. (2007). “ADV measurements around a cluster microform in a shallow mountain stream.” Journal of Hydraulic Engineering, Vol. 133, No. 12 Dordrecht, Netherlands, pp. 1379–1389, DOI: https://doi.org/10.1061/(ASCE)0733-9429(2007)133:12(1379).
Wintenberger, C., Rodrigues, S., Claude, N., Jugé, P. Bréhéret, J., and Villar, M. (2015). “Dynamics of nonmigrating mid-channel bar and superimposed dunes in a sandy-gravelly river (Loire River, France).” Geomorphology, Vol. 248, pp. 185–204, DOI: https://doi.org/10.1016/j.geomorph.2015.07.032.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Khan, M.A., Sharma, N. Investigation of Coherent Flow Turbulence in the Proximity of Mid-Channel Bar. KSCE J Civ Eng 23, 5098–5108 (2019). https://doi.org/10.1007/s12205-019-1430-2
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s12205-019-1430-2