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Effect of apron roughness on flow characteristics and scour depth under submerged wall jets

Abstract

Scour downstream of smooth and rough rigid aprons under wall jets has been studied experimentally. Effect of apron roughness on scour has been investigated, and quantification of reduction in the scour depth due to rough apron has been performed. Characteristics of velocity and turbulence over smooth and rough aprons as well as within the scour hole have been analyzed to study the behavior of the jet and its interaction with the rough apron. Results show that there is a significant reduction in the equilibrium scour depth due to roughness. A maximum of 82.8% and a minimum of 31.1% reduction in the equilibrium scour depth was observed due to inducing roughness over the rigid apron. Velocity characteristics establish the cause of reduction in the equilibrium scour depth, which is due to reduction in the erosive capacity of the jet as it moves over the rough apron. The potential core of the jet gets consumed at a much lesser length due to roughness over the apron than over a smooth apron, as the boundary layer develops at a smaller distance. Further, it was observed that it takes a smaller length for the flow to get fully developed under the rough apron as compared with the smooth apron. Based on the results of the present analysis, recommendation can be made for use of roughness over the apron to restrict scour due to wall jets.

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Data availability

All the data used in this study are available from the corresponding author upon request.

Abbreviations

a :

Sluice opening

d 50 :

Median sediment size

d d :

Height of dune crest

d s :

Depth of maximum scour at equilibrium

d st :

Depth of maximum scour at any time t

d t :

Tailwater depth

F :

Jet Froude number

g :

Gravitational acceleration

k s :

Nikuradse's equivalent sand roughness

L :

Length of apron downstream of sluice gate

s :

Specific gravity of sediment particles

t :

Time of scouring

u :

Horizontal velocity component

u o :

Local maximum of vertical distribution of u

u + :

\((\overline{{u^{\prime}u^{\prime}}} )^{0.5} /V\)

(u +)o :

Local maximum of vertical distribution of u+

(u +)m :

Maximum value of u+ for an experimental condition

u':

Fluctuation of u

uv'+ :

\(- \overline{{u^{\prime}v^{\prime}}} /V^{2}\)

(uv +)o :

Local maximum of vertical distribution of uv+

(uv +)m :

Maximum value of uv+ for an experimental condition

V :

Issuing jet velocity

v :

Vertical velocity component

v + :

\((\overline{{v^{\prime}v^{\prime}}} )^{0.5} /V\)

(v +)o :

Local maximum of vertical distribution of v+

(v +)m :

Maximum value of v+ for an experimental condition

v':

Fluctuation of v

x :

Streamwise distance from the end of apron

:

x/a

x o :

Length of the scour hole

x s :

Distance of maximum scour depth from apron

y :

Vertical distance from the top surface of apron

ŷ :

y/a

y 1 :

Vertical distance where u: uo/2 and ∂u/∂y < 0

y 2 :

Sequent depth of free jump

δ :

Boundary layer thickness; vertical distance where u: uo

σ g :

Geometric standard deviation of sediment

References

  1. Aamir M, Ahmad Z (2015) Estimation of scour depth downstream of an apron under 2D horizontal jets. Proceedings of HYDRO 2015 International, 20th International Conference on Hydraulics, Water Resources and River Engineering, Indian Institute of Technology Roorkee, India.

  2. Aamir M, Ahmad Z (2016) Review of literature on local scour under plane turbulent wall jets. Phys Fluids 28:105102

    Article  Google Scholar 

  3. Aamir M, Ahmad Z (2017) Prediction of local scour depth downstream of an apron under wall jets. In: Garg V, Singh V, Raj V (eds) Development of Water Resources in India. Water Science and Technology Library, Springer, Cham, 75(32): 375–385.

  4. Aamir M, Ahmad Z (2019) Estimation of maximum scour depth downstream of an apron under submerged wall jets. J Hydroinf 21(4):523–540

    Article  Google Scholar 

  5. Aderibigbe O, Rajaratnam N (1998) Effect of sediment gradation on erosion by plane turbulent wall jets. J Hydraul Eng 124(10):1034–1042

    Article  Google Scholar 

  6. Ali KHM, Lim SY (1986) Local scour caused by submerged wall jets. Proc Inst Civ Eng 81(2):607–645

    Google Scholar 

  7. Bashiri H, Sharifi E, Singh VP (2018) Prediction of local scour depth downstream of sluice gates using harmony search algorithm and artificial neural networks. J Irrig Drain Eng 144(5):06018002

    Article  Google Scholar 

  8. Carstens MR (1966) Similarity laws for localized scour. J Hydraul Div 92(3):13–36

    Article  Google Scholar 

  9. Chatterjee SS, Ghosh SN (1980) Submerged horizontal jet over erodible bed. J Hydraul Div 106(11):1765–1782

    Article  Google Scholar 

  10. Chatterjee SS, Ghosh SN, Chatterjee M (1994) Local scour due to submerged horizontal jet. J Hydraul Eng 120(8):973–992

    Article  Google Scholar 

  11. Dey S, Sarkar A (2008) Characteristics of submerged jets in evolving scour hole downstream of an apron. J Eng Mech 134(11):927–936

    Article  Google Scholar 

  12. Hassan NMKN, Narayanan R (1985) Local scour downstream of an apron. J Hydraul Eng 111(11):1371–1385

    Article  Google Scholar 

  13. Hogg AJ, Huppert HE, Dade WB (1997) Erosion by planar turbulent wall jets. J Fluid Mech 338:317–340

    Article  Google Scholar 

  14. Jesson M, Sterling M, Bridgeman J (2013) Despiking velocity time-series–optimisation through the combination of spike detection and replacement methods. Flow Meas Instrum 30:45–51

    Article  Google Scholar 

  15. Kartal V, Emiroglu ME (2021) Local scour due to water jet from a nozzle with plates. Acta Geophys 69:95–112

    Article  Google Scholar 

  16. Laursen, E.M. (1952). Observations of the nature of scour. Proceedings of the 5th Hydraulic Conference, University of Iowa, Iowa City, Iowa, 34, 179–197.

  17. Long D, Steffler PM, Rajaratnam N (1990) LDA study of flow structure in submerged hydraulic jump. J Hydraul Res 28(4):437–460

    Article  Google Scholar 

  18. Pandey M, Lam WH, Cui Y, Khan MA, Singh UK, Ahmad Z (2019) Scour around spur dike in sand–gravel mixture bed. Water 11(7):1417

    Article  Google Scholar 

  19. Pandey M, Sharma PK, Ahmad Z, Singh UK, Karna N (2018) Three-dimensional velocity measurements around bridge piers in gravel bed. Mar Georesour Geotechnol 36(6):663–676

    Article  Google Scholar 

  20. Pandey M, Valyrakis M, Qi M, Sharma A, Lodhi AS (2021) Experimental assessment and prediction of temporal scour depth around a spur dike. Int J Sedim Res 36(1):17–28

    Article  Google Scholar 

  21. Rajaratnam N (1976) Turbulent jets. Elsevier Science Publishing Company, Amsterdam

    Google Scholar 

  22. Rajaratnam N (1981) Erosion by plane turbulent jets. J Hydraul Res 19(4):339–358

    Article  Google Scholar 

  23. Rajaratnam N, Macdougall RK (1983) Erosion by plane wall jets with minimum tail water. J Hydraul Eng 109(7):1061–1064

    Article  Google Scholar 

  24. Rouse H. (1939). Criteria for similarity in transportation of sediment. Proceedings of the 1st Hydraulic Conference, Iowa City, Iowa, 33–49.

  25. Santos R, Carvalho E, Lima MM, Aleixo R (2021) Time evolution of the scour induced by a ski jump jet. J Appl Water Eng Res in Press. https://doi.org/10.1080/23249676.2021.1919226

    Article  Google Scholar 

  26. Singh RK, Pandey M, Pu JH, Pasupuleti S, Villuri VGK (2020) Experimental study of clear-water contraction scour. Water Supply 20(3):943–952

    Article  Google Scholar 

  27. Tarapore ZS (1956) Scour below a submerged sluice gate. M.Sc. thesis, University of Minnesota, Minneapolis.

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Correspondence to Mohammad Aamir.

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On behalf of all authors, the corresponding author states that there is no conflict of interest.

Additional information

Communicated by Dr. Michael Nones.

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Aamir, M., Ahmad, Z. Effect of apron roughness on flow characteristics and scour depth under submerged wall jets. Acta Geophys. (2021). https://doi.org/10.1007/s11600-021-00672-9

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Keywords

  • Jets
  • Scour
  • Hydraulic jump
  • Velocity field
  • Turbulence