M. Fathi, A. Honarbakhsh, , M. Rostami, A. Davoudian Dehkordi,
Volume 16, Issue 62 (3-2013)
Abstract
The present paper tries to describe the advantage and improvement of a numerical model when predicting government processes on Flow Rivers. With regard to the important effect of the flow velocity and shear stress forces on river bank erosion, we apply a Two-Dimensional numerical model, named CCHE2D, to simulate river flow pattern at a meandering river Khoshk-e-Rud River of Farsan, 30 Km west of Shahr-e- Kord. Various algorithms and parameters were implemented in a computational fluid dynamic model (CFD) for simulation of two-dimensional (2D) water flow to gain an insight into the capabilities of the numerical model. At this surveying, at first, we applied the topographic maps of the studied location and then, made the model geometry and calculation mesh with diverse dimensions. Finally, using the measured properties of the river flow and the Depth-Average, Two-Dimensional Hydrodynamic Model was run. Then, we obtained the results of model, such as depth and flow velocity at the river meander. Within the scope of the test cases, the model simulated water flow pattern processes at an intake, as well as a steady flow regime in a sine-shaped meandering channel by a 90_channel bend, which is the free-forming meander evolution of an initially straight channel. Because of high accuracy of this numerical model and multiple content of its internal parameters, the evaluation result of model, confirmed the measurement results. Therefore, the parameters gained from the model showed good conformity with measurement parameters at field cross-section. All results matched well with the measurements. The results also showed that using computational fluid dynamics for modeling water flow is one step closer to having a universal predictor for processes in Meandering Rivers
A. Rezaei Ahvanooei, H. Karami, F. Mousavi,
Volume 23, Issue 3 (12-2019)
Abstract
In this research, by using FLOW3D, the performance of non-linear (arced) piano key (PKW-NL) in plan and linear piano key weir (PKW-L), with equal length of weir, was compared. Results showed that nonlinearity of the weir caused 20% increase in the discharge coefficient. Investigating the velocity contours for these two weir models also showed that maximum velocity within the PKW-NL weir structure is about 30% lower than the PKW-L weir. Also, the performance of non-linear piano key weir was evaluated under inward (PKW-IC) and outward (PKW-OC) curvatures to the channel. Results showed that in the case of PKW-IC weir, the discharge coefficient was increased by 8% as compared to the PKW-OC weir. Investigating the pressure contours for these two weir models also shows that the average pressure within the PKW-IC weir structure is about 5% higher than the PKW-OC weir. This increase in pressure leads to a decrease in the speed and better distribution of flow over the weir keys.
R. Gharibvand, M. Heidarnejad, H. A. Kashkouli, H. Hasoonizadeh, A. Kmanbedast,
Volume 24, Issue 1 (5-2020)
Abstract
The flow fields over a trapezoidal labyrinth weir (two-cycle) and a piano key weir were simulated using Flow3D, studying the impact of each model on the flow field in the weirs and the coefficient of discharge in comparison with the available experimental data. Moreover, the models were investigated experimentally in a 12.5 m long, 0.3 m wide, and 0.4 m high rectangular flume under clear-water conditions. The results showed good agreement between the data from the numerical and experimental models. The piano key weirs had a higher coefficient of discharged compared with labyrinth weirs. The coefficient of discharge was observed to increase by 26 percent as the height of the PKW was increased by 50 percent (from 5 to 7.5 cm). This increase was 24 percent for labyrinth weirs.
H. Noury Hasanabady, M.r. Kavianpour, A. Khosrojerdi, H. Babazadeh,
Volume 26, Issue 3 (12-2022)
Abstract
Using a rough bed for spillway compare to common dissipation methods such as stilling basins, stepped spillways, ski jumps, and bed elements may be more efficient to boost energy dissipation. In this research, the impact of spillway continuous bed roughness on energy dissipation was investigated. For this purpose, a non-dimensional relationship was developed, and by calibrating the numerical model based on the present experimental study, energy dissipation over the spillway for three slopes of 15, 22.5, and 30 (degree) with six roughness sizes of 0.0, 0.005, 0.0072, 0.0111, 0.016, and 0.022 (m) and three discharges of 170, 110, and 90 (lit/s) was investigated. Based on the present results, using a rough bed spillway will increase energy dissipation. Also, the ratio of energy lost per meter length of rough bed spillway to that of smooth spillway increases by chute slope. The results showed that the highest amount of relative energy consumption in the presence of roughness was related to the slope of 22.5 degrees and 22.2 mm for roughness (85%), and the lowest relative energy consumption was observed in the control state (25%). As a result of the present study, a natural rough bed without concrete coating has befitted in terms of environmental aspects, construction cost, and energy loss.
