scholarly journals 3D SPH Simulation of Dynamic Water Surface and Its Interaction with Underlying Flow Structure for Turbulent Open Channel Flows Over Rough Beds

2018 ◽  
Vol 01 (02) ◽  
pp. 1840003
Author(s):  
Eslam Gabreil ◽  
Simon Tait ◽  
Andy Nichols ◽  
Giulio Dolcetti
Keyword(s):  
Free Surface ◽  
Water Surface ◽  
Open Channel ◽  
Free Surface Flows ◽  
Channel Flows ◽  
Open Channel Flows ◽  
Eddy Viscosity Model ◽  
Rough Bed ◽  
Sph Model ◽  
Surface Patterns

In this study, a fully 3D numerical model based on the Smoothed Particle Hydrodynamics (SPH) approach has been developed to simulate turbulent open channel flows over a fixed rough bed. The model focuses on the study of dynamic free surface behavior as well as its interaction with underlying flow structures near the rough bed. The model is improved from the open source code SPHysics ( http://www.sphysics.org ) by adding more advanced turbulence and rough bed treatment schemes. A modified sub-particle-scale (SPS) eddy viscosity model is proposed to reflect the turbulence transfer mechanisms and a modified drag force equation is included into the momentum equations to account for the existence of roughness elements on the bed as well as on the sidewalls. The computed results of various free surface patterns have been compared with the laboratory measurements of the fluctuating water surface elevations in the streamwise and spanwise directions of a rectangular open-channel flow under a range of flow conditions. The comparison has demonstrated that the proposed 3D SPH model can simulate well the complex free surface flows over a fixed rough bed.

Open channel flows with submerged obstructions

1989 ◽  
Vol 206 ◽  
pp. 155-170 ◽  
Author(s):  
Frrédéric Dias ◽  
Jean-Marc Vanden-Broeck
Keyword(s):  
Free Surface ◽  
Stagnation Point ◽  
Open Channel ◽  
Free Surface Flows ◽  
Channel Flows ◽  
Two Dimensional ◽  
Open Channel Flows ◽  
Surface Flows ◽  
Arbitrary Size ◽  
Local Solutions

Free-surface flows past a submerged triangular obstacle at the bottom of a channel are considered. The flow is assumed to be steady, two-dimensional and irrotational; the fluid is treated as inviseid and incompressible and gravity is taken into account. The problem is solved numerically by series truncation. It is shown that there are solutions for which the flow is suberitical upstream and supercritical downstream and other flows for which the flow is supercritical both upstream and downstream. The latter flows have limiting configurations with a stagnation point on the free surface with a 120° angle at it. It is found that solutions exist for triangular obstacles of arbitrary size. Local solutions are constructed to describe the flow near the apex when the height of the triangular obstacle is infinite.

Additional spanwise vortices near the free surface in open channel flows

2021 ◽  
Vol 924 ◽  
Author(s):  
Yanchong Duan ◽  
Qiang Zhong ◽  
Guiquan Wang ◽  
Qigang Chen ◽  
Fujun Wang ◽  
...  
Keyword(s):  
Free Surface ◽  
Open Channel ◽  
Channel Flows ◽  
Open Channel Flows

Abstract

On the definition of the shear velocity in rough bed open channel flows

2006 ◽  
Author(s):  
C Manes ◽  
D Pokrajac ◽  
I McEwan ◽  
J Finnigan ◽  
V Nikora
Keyword(s):  
Open Channel ◽  
Shear Velocity ◽  
Channel Flows ◽  
Open Channel Flows ◽  
Rough Bed ◽  
Definition Of

scholarly journals Flow Structures of the Air-Water Layer in the Free Surface Region of High-Speed Open Channel Flows

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Feng Jiang ◽  
Weilin Xu ◽  
Jun Deng ◽  
Wangru Wei
Keyword(s):  
Free Surface ◽  
Layer Thickness ◽  
High Speed ◽  
Open Channel ◽  
Water Layer ◽  
Channel Flows ◽  
Flow Structures ◽  
Air Velocity ◽  
Open Channel Flows ◽  
The Relationship

In hydraulic engineering, intense free surface breakups have been observed to develop in high-speed open channel flows, resulting in a mixed air-water layer near the free surface that grows with the development of self-aeration. This region is characterized by a substantial number of droplets coexisting with an induced air layer above. Little information about this droplet layer is currently available and no practicable approach has been proposed for predicting the parameters of the induced air layer based on the related flow structures in the droplet layer. In this research, laboratory experiments were accordingly conducted to observe the detailed droplet layer development in terms of layer thickness, droplet size, and frequency distributions under comparative flow conditions. Based on the simplified droplet layer roughness determined using the experimentally measured mean droplet size, the classical power-law of boundary layer theory was applied to provide an analytical solution for the air velocity profile inside the air layer. The relationship of air layer growth to droplet layer thickness, which is a key factor when determining the air velocity distribution, was also established, and the analytical results were proven to be in reasonable agreement with air velocity profiles presented in the literature. By determining the relationship between droplet layer properties and air velocity profiles, the study establishes a basis for the improved modeling of high-speed open channel flows.

Simulating 2D open-channel flows through an SPH model

2012 ◽  
Vol 34 ◽  
pp. 35-46 ◽  
Author(s):  
I. Federico ◽  
S. Marrone ◽  
A. Colagrossi ◽  
F. Aristodemo ◽  
M. Antuono
Keyword(s):  
Open Channel ◽  
Channel Flows ◽  
Open Channel Flows ◽  
Sph Model
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