NUMERICAL SIMULATION AND EXPERIMENTAL STUDY OF HYDRAULIC PERFORMANCE OF CIRCULAR CRESTED NORMAL WEIRS

BAHZAD MOHAMMAD ALI  NOORI; BSHKOJ SIDQI  HUSSEIN; NAEEMA THAHER  AAREF

doi:10.26682/sjuod.2022.25.1.8

BAHZAD MOHAMMAD ALI NOORI Dept. of Civil Engineering, College of Engineering, University of Duhok, Kurdistan Region-Iraq
BSHKOJ SIDQI HUSSEIN Dept. of Water Resources Engineering, College of Engineering, University of Duhok, Kurdistan Region-Iraq
NAEEMA THAHER AAREF Dept. of Mechanical Engineering, College of Engineering, University of Duhok, Kurdistan Region-Iraq

DOI: https://doi.org/10.26682/sjuod.2022.25.1.8

Keywords: Numerical simulation; Normal weirs; Circular crests; Hydraulic performance; Discharge magnification

Abstract

Weirs are simple control structures usually built across channels for water storage and measurement
of flow rates. The main target of the present study is to numerically simulate and experimentally study the
hydraulic performance of circular crested normal weirs. For numerical simulation, the commercial
package ANSYS CFX is utilized adopting tetrahedrons mesh with a maximum total number of 1932301
elements, while, for the experimental study nine physical models are manufactured and tested having
different crest diameters and various weir heights. Numerical simulation results demonstrated that the
ANSYS CFX software is highly capable for simulating circular crested normal weirs showing quite good
agreements in water surface profiles and 4.3% mean percentage error in upstream head above crest,
while, the software showed 6.8% mean percentage error in estimating discharge coefficient. A simple
empirical expression is obtained for the estimation of coefficient of discharge in terms of ratio of upstream
head to weir height and the ratio of upstream head to crest diameter with a coefficient of correlation =
0.88. The flow rate magnification is found increasing with the increase of upstream relative head and the
best performance of the weir is found when the ratio of crest diameter to weir height = 0.33 at which the
highest increase in flow rate is observed ranging between 25.41% and 32.14% compared with sharp
crested weirs having the same height and the same length of crest

Downloads

Download data is not yet available.

References

AAREF, N. 2016. Hydraulic Performance of Sharp
and Circular Crested Triangular Plan Form
Weirs. M.Sc. Thesis, University of Duhok,
Duhok, Iraq.
ANSYS-CFX-HELP. Release 14.0 [Online].
Available: http://www.ANSYS.com.
[Accessed 2011].
BACHAYA, A., HASHMI, H. N., BALUCH, M. A.,
ALI, Z. & LATIF, A. 2019. Flow
Characteristics over the Weir with
Semicircular Crest in Normal and Oblique
Plane. Technical Journal, University of
Engineering and Technology (UET), Taxila,
Pakistan, 24(1), 1-8.
CHANSON, H. & MONTES, J. S. 1998. Overflow
Characteristics of Circular Weirs: Effects of
Inflow Conditions. Journal of Irrigation and
Drainage Engineering, 124(3), 152-162.
CHILMERAN, T. A. H. 1996. Characteristics of
Flow over Normal and Oblique Weirs with
Semicircular Crests. M.Sc. Thesis, University
of Mosul, Mosul, Iraq.
CHOW, V. T. 1959. Open Channel Hydraulics. New
York: McGraw-Hill Book Company. Inc.
CROOKSTON, B. M. & TULLIS, B. P. 2011. The
Design and Analysis of Labyrinth Weirs. 21st
Century Dam Design, Advances and
Adaptations, 31st Annual USSD Conferences.
San Diego, California; April 11-15.
JOHNSON, M. C. 2000. Discharge Coefficient
Analysis for Flat-topped and Sharp Crested
Weirs. Irrigation Science, 19, 133-137.
KINDSVATER, C. E. & CARTER, R. W. 1957.
Discharge Characteristics of Rectangular
Thin-Plate Weirs. Journal of the Hydraulics
Division, 83, 1453-1-1453-36.
LUX, F. & HINCHLIFF, D. L. 1985. Design and
Construction of Labyrinth Spillways.
Transactions of the 15th International
Congress on Large Dams. Lausanne,
Switzerland, 4, 249-74.
NIKSERESHT, A. H., ALISHANI, M. M. &
EMDAD, H. 2009. Generalized Curvilinear
Coordinate Interface Tracking in the
Computational Domain. Scientia Iranica,
16(1), 64-74.
NOORI, B. M. A. 1985. Investigation of Stepped
Blocks Protecting Weir Slopes. Ph. D. Thesis,
University of Southampton, Southampton,
England.
NOORI, B. M. & AAREF, N. T. 2017. Hydraulic
Performance of Circular Crested Triangular
Plan Form Weirs. Arabian Journal for Science
and Engineering, 42(9), 4023-4032.
NOORI, B. M. & CHILMERAN, T. A. 2005.
Characteristics of Flow over Normal and
Oblique Weirs with Semicircular Crests. AlRafidain Engineering Journal (AREJ), 13(1),
49-61.
NOORI, B. M. A. 2020. Hydraulic Performance of
Circular Crested Oblique Weirs. Ain Shams
Engineering Journal, 11(4), 875-888.
REHBOCK, T. 1929. The River-hydraulic
Laboratory of the Technical University at
Karlsruhe, American Society of Mechanical
Engineers.
ROUSE, H. 1936. Discharge characteristics of the
free overfall: Use of crest section as a control
provides easy means of measuring discharge.
Civil Engineering, 6, 257-260.
BRITISH STANDARD INSTITUTION. 1965.
Methods of measurement of liquid flow in
open channels. London, England; BS 3680,
Part 4A.
TINGEY, S. E. 2011. Discharge coefficients of
oblique weirs. M.Sc., Utah State University,
Logan, Utah, U.S.A.
TULLIS, J. P., AMANIAN, N. & WALDRON, D.
1995. Design of labyrinth spillways. Journal of
hydraulic engineering, 121, 247-255.