### 1. Introduction

### 2. Materials and Methods

### 2.1. Input Data

### 2.2. Arrangements of the Channel reach to Carry out the Physical Modeling

### 2.3. Glimpses of the Physical Modeling of the Downstream Reach in Dry Phase

### 2.4. Model Calibration and Hydraulic Testing

### 2.5. Measurements of Water Levels and Velocities at Different Discharges

### 2.6. k-Epsilon (k-ɛ) Model

*C*

*,*

_{μ}*C*

_{ɛ}_{1},

*C*

_{ɛ}_{2},

*σ*

*and*

_{k,}*σ*

*. The transport equation is given below Eq. (1) was considered for the dissipation rate [4]:*

_{ɛ}##### (1)

$$\frac{\partial \in}{\partial t}+{U}_{i}\frac{\partial \in}{\partial {x}_{i}}=\frac{\in}{k}({C}_{\in 1}P-{C}_{\in 2}\in )+\frac{\partial}{\partial {x}_{i}}\left(\frac{{v}_{t}}{{\sigma}_{\in}}\frac{\partial \in}{\partial {x}_{i}}\right)$$${\scriptstyle \frac{\partial \mathrm{\varepsilon}}{\partial t}}=Rate\hspace{0.17em}of\hspace{0.17em}Change\hspace{0.17em}of\hspace{0.17em}\mathrm{\varepsilon}$

$Ui\hspace{0.17em}{\scriptstyle \frac{\partial \mathrm{\varepsilon}}{\partial xi}}=Transport\hspace{0.17em}of\hspace{0.17em}\mathrm{\varepsilon}\hspace{0.17em}\text{by\hspace{0.17em}convection}$

${\scriptstyle \frac{\mathrm{\varepsilon}}{k}}\hspace{0.17em}(C{\varepsilon}_{1}\hspace{0.17em}P-C{\varepsilon}_{2}\hspace{0.17em}\varepsilon )=Production\hspace{0.17em}and\hspace{0.17em}dissipate\hspace{0.17em}rate\hspace{0.17em}of\mathrm{\varepsilon}$

${\scriptstyle \frac{\partial}{\partial xi}}\hspace{0.17em}\left({\scriptstyle \frac{Vt}{\mathrm{\sigma}\varepsilon}}{\scriptstyle \frac{\partial \mathrm{\varepsilon}}{\partial xi}}\right)=Turbulent\hspace{0.17em}Transport\hspace{0.17em}of\hspace{0.17em}\mathrm{\varepsilon}$

### 2.7. Reynolds Stress (RS) Model

##### (2)

$${\scriptstyle \frac{\partial Rij}{\partial t}}+Cij=Pij+Dij-\varepsilon ij+\mathrm{\Pi}ij+\mathrm{\Omega}ij$$*R*

*= rate of change of Reynolds stresses,*

_{ij}*C*

*= transport of convection,*

_{ij}*P*

*= rate of production of Reynolds stresses,*

_{ij}*D*

_{ij}*=*transport of stresses by diffusion,

*ɛ*

*= dissipation rate of stresses,*

_{ij}*Π*

*= stresses transport due to turbulent pressure–strain interactions, and*

_{ij}*Ωij*= transport of stresses due to rotation [7].

### 2.8. Numerical Simulation

### 2.9. Input Data Used for the Numerical Simulation in ANSYS FLUENT

### 2.10. Comparison between Physical Modeling and Numerical Simulations

### 2.11. Other Flow and Turbulence Properties

### 3. Results

### 3.1. Mesh Generation

### 3.2. Various Flow and Turbulence Parameters Obtained through ANSYS FLUENT Simulation

For 500,000 cusecs (less than design discharge of Chashma Barrage)

For 800,000 cusecs (at design discharge of Chashma Barrage)

For 957,289 cusecs (greater than design discharge of Chashma Barrage)

For 50,000 cusecs (less than design discharge of Chashma Barrage)

For 500,000 cusecs (less than design discharge of Chashma Barrage)

For 800,000 cusecs (at design discharge of Chashma Barrage)

For 957,289 cusecs (greater than design discharge of Chashma Barrage)