Comparative Study of Boundary Layer Thickness for Flow over Spillways

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Published: 2023-04-05

Page: 107-116

N. Suresh Kumar

College of Engineering (A), Osmania University, Hyderabad, India.

S. V. S. N. D. L. Prasanna *

College of Engineering (A), Osmania University, Hyderabad, India.

*Author to whom correspondence should be addressed.


Spillways provide a safe passage for excess or flood water from the reservoir. The hydraulic parameters viz., Depth of flow (DoF) over the spillway, Boundary Layer Thickness (BLT), wall shear stress, and skin friction coefficient for flow over spillways are helpful in evaluating the flow resistance over the spillways. These parameters can be made use of in the design of energy dissipators. In view of the need for the estimation of the above parameters, the primary objective of the present study is to analytically estimate the above parameters using the applicable equations available in the literature. These parameters were evaluated for four different discharges. The second objective was to conduct the simulation studies in ANSYS – Fluent software on a 1:100 scale model of the Nagarjuna Sagar Dam spillway section by considering Froude's model law. From the present study, it was evident that the difference between the BLT and computed depth of flow was ranging from 1% to 25% for the selected discharges evaluated using the conventional equations. Based on the methodology adopted in the present investigation, a new equation is proposed for estimating the thickness of the boundary layer for hydraulically rough surfaces. Further, with the proposed equation the values of BLT and DoF were coinciding a one point having error percentage less than 0.1%. The simulation values for wall shear stress were in corroboration with the analytical values for the selected flow rates with less than 1% error.

Keywords: Boundary layer thickness, smooth, rough, velocity, depth of flow, shear stress

How to Cite

Kumar, N. S., & Prasanna, S. V. S. N. D. L. (2023). Comparative Study of Boundary Layer Thickness for Flow over Spillways. Asian Research Journal of Current Science, 5(1), 107–116. Retrieved from


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António Muralha. José F. Melo, Helena M. Ramos. Assessment of CFD solvers and turbulent models for water free jets in spillways. Fluids. 2020;5:104:1-17. DOI:https://doi:10.3390/fluids5030104

Chadwick Andrew, John Morfett. Hydraulics in civil and environmental engineering. E & FN Spon an imprint of Routledge, London. 1998;415-430.

Kalita HM, Das R, Hajong A, Kumar N, Kharnaior D, Dkhar HC. Experimental and Numerical Flow Simulation over Weirs. Water Resources. 2019;46(6):934–943. DOI:

Fathi-moghaddam M, Tavakol MT, and Rahmanshahi M. Numerical simulation of the hydraulic performance of triangular and trapezoidal gabion weirs in free flow condition. Flow Meas Instrum. 2018;62:93–104.


Öznur Kocaer& Alpaslan Yarar. Experimental and Numerical Investigation of Flow Over Ogee Spillway. Water Resources Management, 2020;34:3949–3965. DOI:

Falvey, H.T. Air-water Flow in Hydraulic Structures, USBR Engineering Monograph, 1980;41:16-18.

Ven Te Chow. Open-channel hydraulics. McGraw Hill Book Company INC, New York; 1959.

Gopal Rao M. Nagarjuna Sagar – The Epic of a Great Temple of Humanity, Bharatiya Vidya Bhavan, Bombay, Chapter-7, Design, and Instrumentation. 1979;137-140.

Stephen, T. Maynord. General Spillway Investigation (Hydraulic Model Investigation), Technical Report, HL-85-1, Department of Navy, Waterways Experiment Station, U.S. Army Corps of Engineers, Mississippi. 1985;4-10.

Prasanna SVSNDL. Turbulence modelling for selective hydraulic engineering applications. Ph.D. Thesis, Dept. of Civil Engg., Osmania University, Hyderabad, TS. 2019;49-77.

Wilcox, David C. Turbulence Modeling for CFD, DCW Industries, Inc. California, 2006;122-130.

Suresh Kumar N, Prasanna SVSNDL. Turbulence modelling for estimation of hydraulic jump height. Recent Trends in Fluid Mechanics. 2018;5(3):1-11.

Prasanna SVSNDL, Suresh Kumar N. Estimation and simulation of pressures on the profile of the spillway. International Journal of Technical Innovation in Modern Engineering and Science, 2019;5(7):442-448.

Prasanna SVSNDL, Suresh Kumar N. Simulation and analytical estimation of spillway flip bucket parameters. International Journal of Innovative Technology and Exploring Engineering. 2019;8(12):4062-4066.

Oscar Castro-Orgaz, Willi H. Hager. Drawdown curve and turbulent boundary layer development for chute flow. Journal of Hydraulic Research. 2010;48(5):591-602. DOI:10.1080/00221686.2010.507337.