Two-dimensional Numerical modeling of rolling waves in chutes and analyze the factors affecting the formation of them

Document Type : Technical Note

Authors

1 M.Sc. Graduate, Department of Civil Engineering, Faculty of Engineering, Shahid Bahonar University of Kerman, Kerman, Iran

2 Assistant Professor, Department of Civil Engineering, Faculty of Engineering, Shahid Bahonar University of Kerman, Kerman,

Abstract

Roll waves create instabilities and turbulent behavior in channels and chutes that affect downstream
hydraulic structures. The present study aims to provide a numerical model to simulate the roll waves
in the turbulent regime and analyze the conditions and factors affecting the formation of the roll
waves on the free surface. In the present model, the governing equations consist of the depthaveraged
Navier Stokes equations that are discretized by finite volume method. The HLLC method
is selected. To achieve second order accuracy in time and space, the TVD-WAF scheme is used. For
modeling the turbulence effects, the standard k-ɛ turbulence model is used. Then the results of the
present model are compared with the experimental data and the analytical solutions. The results
show that applying a regular perturbation at the inlet of the channel causes periodic roll waves and
the amplitude and period of the periodic roll waves are independent of the perturbation amplitude at
the inlet of the channel. But if the perturbation amplitude is a greater percentage of normal depth, the
distance of formation of roll waves is shorter and waves evolve faster than other conditions. In
addition, the results analysis shows that the Froude number and magnitude of the discharge affect the
formation and evolution of waves.

Keywords


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  • Receive Date: 07 May 2017
  • Revise Date: 07 December 2017
  • Accept Date: 15 December 2017
  • First Publish Date: 21 March 2018