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Showing 4 results for Pourabdollah

N. Pourabdollah, T. Honar, R. Fatahi,
Volume 18, Issue 67 (Spring 2014)
Abstract

Most of researches related to hydraulic jump have been done on horizontal and rough beds, and little attempt has been made on rough beds with adverse slopes. The aim of this study was to investigate the influence of rough beds with adverse slope on hydraulic jump characteristics. The variations of energy loss in stilling basins with three adverse slopes and three different roughnesses were studied. Results showed that increase of roughness caused that relative depth of jump in stilling basins with rough bed and adverse slope decreased as compared to horizontal smooth beds. The experiments were performed on rough beds in different conditions where Froude number ranging between 4.9 and 7.8. Result showed that reduction of relative depth was about 31.15%. Results also showed that in such cases the relative energy losses are more than that for classic conditions.
N. Pourabdollah, J. Abedi Koupai, M. Heidarpour, M. Akbari,
Volume 25, Issue 4 (Winiter 2022)
Abstract

In this study accuracy of the ANFIS and ANFIS-PSO models to estimate hydraulic jump characteristics including sequence depth ratio, the jump length, the roller length ratio, and relative energy loss was evaluated in stilling basin versus laboratory results. The mentioned characteristics were measured in the stilling basin with a rectangular cross-section with four different adverse slopes, four diameters of bed roughness, four heights of positive step, three Froude numbers, and four discharges. The average statistical parameters of NRMSE, CRM, and R2 for estimating hydraulic jump characteristics with the ANFIS model were 0.059, -0.001, and 0.989, respectively. While, the mean values of these parameters for the ANFIS-PSO model were 0.185, 0.002, and 0.957, respectively. The results indicated that these models were capable of estimating hydraulic jump parameters with high accuracy. However, the ANFIS model was moderately more accurate than the ANFIS-PSO model to estimate the sequence depth ratio, the jump length, the roller length ratio, and relative energy loss.

N. Pourabdollah, M. Heidarpour, Jahangir Abedi-Koupai,
Volume 27, Issue 3 (Fall 2023)
Abstract

Hydraulic jump is used for dissipation of kinetic energy downstream of hydraulic structures such as spillways, chutes, and gates. In the present study, the experimental measurements and numerical simulation of the free hydraulic jump by applying Flow-3D software in six different conditions of adverse slope, roughness, and positive step were compared. It should be noted that two turbulence models including k-ε and RNG were used for numerical simulation. Based on the results, simulation accuracy using the RNG model was more than the k-ε model. The statistical indices of NRMSE, ME, NS, and R2 for comparing the water surface profile were obtained at 34.3, 0.0052, 0.995, and 983 for the application of the RNG model, respectively. Also, using the RNG model, the values of these indices for the velocity profile were obtained at 14.92, 0.127, 0.9982, and 962, respectively. In general, the error of the simulated water surface and velocity profile were obtained at 5.31 and 12.4 percent, respectively. Moreover, the maximum error of the numerical simulation results of D2/D1, Lj/D2, and Lr/D1 was ±12, ±12, and 16%, respectively. Therefore, the use of Flow-3D software with the application of the RNG turbulence model is recommended for numerical simulation of the hydraulic jump in different situations.

M. Heidarpour, Kimia Akhavan, N. Pourabdollah,
Volume 28, Issue 3 (Fall 2024)
Abstract

One of the ways to improve the characteristics of the hydraulic jump in the stilling basin is to use natural and artificial roughness. Recently, due to the advantages of immersed plates compared to other non-continuous artificial roughness, such as the smaller number of these and the vanes' ability to design their geometry and arrangement, it has been approached more. In this article, the effect of submerged vanes with three contact angles of 45°, 75°, and 90° has been investigated on the improvement of the characteristics of a hydraulic jump and its effect on parameters such as the depth ratio, relative length, energy loss rate, and bed shear force coefficient has been evaluated. The results of this research showed that the average effect of submerged vanes on reducing the depth ratio, jump length, and roller length compared to the classical mode is 9.4%, 24.6%, and 28.4%, respectively and the average relative energy loss is 5.5% compared to the classical state and maximum relative energy loss at the angle of 90 degrees of submerged vanes is 6.5%. Considering these results and other conditions such as ease of construction and use, stabilization, and reduction of economic costs among the available choices of sunken vanes, the angle of incidence of 75° is a suitable option for the optimal design of the stilling basin.


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