Comparison of Subcritical and Supercritical Flow Patterns Within Triangular Channels Along the Side Weir
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Hamed Azimi
Abstract
Side weirs with triangular channel are used as flow controlling devices in draining and irrigation networks. By installing a side weir on the main conduits side walls, the runoff overflows from the weir and are conducted toward the diversion channel. In this study, changing of the flow free surface and the turbulence of the flow field in triangular channels with side weir are numerically simulated using volume of fluid (VOF) scheme and RNG k–ε turbulence model. In the present paper, the pattern of the spatially varied flow with decreasing discharge in both subcritical and supercritical flow regimes for triangular channels with side weirs was simulated. The present numerical model has precisely predicted the changes of the water surface and the specific energy. In subcritical regime, the flow depth is from the beginning of the weir toward its end is followed by an increase and in supercritical conditions is followed by a reduction in depth. For both subcritical and supercritical regimes, a drop in the surface in the first third of the weir’s opening and a surface jump in the final third of its length has occurred. Along the mentioned surface jump the amount of the kinetic energy increases and the potential energy reduces. According to results of the simulation, the maximum longitudinal velocity for subcritical flow regime occurs in the first third of the length of the side weir and for supercritical flow regime, almost in the middle of the weir opening happens. In both subcritical and supercritical regimes, the maximum transverse velocity has occurred in the final third of the length of the side weir.
List of symbols
Constant coefficient
Specific energy in the main channel
Fluid volume fraction in a cell
Acceleration gravity
Turbulence kinetic energy
Side weir length
Side weir height
Pressure
Discharge in the main channel
Discharge at Section 1 in the main channel
Discharge over the side weir
Bed slope of the main channel
Width of the channel at the water surface
Turbulent length scale
Time
Velocity components
Wall shear velocity
Longitudinal component of velocity over crest of side weir
Lateral component of velocity over crest of side weir
Vertical component of velocity over crest of side weir
Direction of Cartesian coordinates
Distance from upstream of the weir
Distance of the cell center from the solid wall
Non-dimensional parameter
Depth of the flow at Section 1 in the main channel
Depth of the flow at Section 2 in the main channel
bottom angle of the triangular channel
Kronecker delta
Turbulence dissipation rate
Kinematic viscosity
Turbulent eddy-viscosity
Fluid density
Angle of the spilling jet
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©2016 by De Gruyter
Articles in the same Issue
- Frontmatter
- Existence of Solutions of a New Class of Impulsive Initial Value Problems of Singular Nonlinear Fractional Differential Systems
- Lump-Type Solutions to the (3+1)-Dimensional Jimbo-Miwa Equation
- Comparison of Subcritical and Supercritical Flow Patterns Within Triangular Channels Along the Side Weir
- Existence of Solutions for Schrödinger–Kirchhoff Type Problems Involving Nonlocal Elliptic Operators
- Application of Fractional Techniques in the Analysis of Forest Fires
- Discharge Coefficient of Rectangular Side Weirs on Circular Channels
- Backward Bifurcation in a Fractional-Order SIRS Epidemic Model with a Nonlinear Incidence Rate
- Auxiliary Equation Method for Fractional Differential Equations with Modified Riemann–Liouville Derivative
Articles in the same Issue
- Frontmatter
- Existence of Solutions of a New Class of Impulsive Initial Value Problems of Singular Nonlinear Fractional Differential Systems
- Lump-Type Solutions to the (3+1)-Dimensional Jimbo-Miwa Equation
- Comparison of Subcritical and Supercritical Flow Patterns Within Triangular Channels Along the Side Weir
- Existence of Solutions for Schrödinger–Kirchhoff Type Problems Involving Nonlocal Elliptic Operators
- Application of Fractional Techniques in the Analysis of Forest Fires
- Discharge Coefficient of Rectangular Side Weirs on Circular Channels
- Backward Bifurcation in a Fractional-Order SIRS Epidemic Model with a Nonlinear Incidence Rate
- Auxiliary Equation Method for Fractional Differential Equations with Modified Riemann–Liouville Derivative
