Generally, circular channels are used in urban sewage systems where the flow is a three phase flow including water, air, and sediments. Accordingly, there are many studies carried out by different researchers related to flow within sewage channels. In current study, the Froude number of three phase flow within sewer channels is predicted using Extreme Learning Machine (ELM). Using parameters affecting the Froude number, 127 various ELM models were defined. The superior model was then introduced. For instance, for the superior model as a function of volumetric sediment concentration, the ratio of the particle size to overall hydraulic radius and overall friction factor for sediment load of 60% and 40% in train and test, respectively, the R2, MAPE and RMSE in testing mode were calculated as 0. 856, 0. 117, and 0. 738, respectively. In addition, the results of superior model were compared with Artificial Neural Network (ANN) and support Vector Machine (SVM) models. Analyses of modeling results showed that extreme learning machine simulated the aim function with more accuracy.

The supercritical flow as the inflow at upstream of the vertical drops can produce a considerable impact, destruction and erosion at the downstream of drops influence by fall and collision. Therefore in this study, with the aim of evaluation and prediction of the general behavior of hydraulic parameters in vertical drops with the supercritical flow at upstream, 55 experiments were carried out with various discharges and Froude numbers. The experimental results indicated that in the supercritical flows, by increasing the relative critical depth and Froude numbers, the relative length of drop, the relative length of splashing and the relative total length of the drop were increased. However, by increasing the relative critical depth and Froude number, the relative depth of the pool initially increases and then decreases, and the relative energy loss is initially reduced and then increased. By increasing the Froude number at a constant relative critical depth, the relative length of the drop, the relative length of splashing, the relative total length of drop and the relative energy loss increases, and relative depth of the pool decreases. Also, in a constant Froude number, by increasing the relative critical depth, the relative length of drop, the relative length of splashing, the relative total length of the drop and relative depth of the pool increase, and the relative energy loss decreases. The results of the present study with the larger range of Froude number were compared with the previous studies and were studied the reasons for the agreement or disagreement.

In this research, the numerical method of computational fluid dynamics and dimensionless pa-rameter of Froude number have been applied to determine the flow regime over ogee spillways. Froude number is a dimensionless dynamic parameter calculated using the square root of the ratio of inertia force and gravitational force. Considering that the study of the regimes of flow over hydraulic structures especially spillways is of great importance, and as the most applied spillway is ogee one, therefore it is required to study such structures. To study the sensitivity of the di-mensionless parameters of Froude number and velocity using in the proper calculation of the profile of the flow over ogee spillway the software of fluent computational fluid dynamics soft-ware has been used. Based on Gauss-Seidel convergence condition applied for the convergence and control of equations, the step time of 0.01 second, quad pave meshing and RNG k-e turbu-lence model have been used. The results of this research shows that the decrease of reference de-sign head by 10, 20, and 30 percent leads to the decrease of reference average Froude number and reference average velocity of the flow over ogee spillway by 7.646, 15.2 18.835, and 6.519, 12.787, and 26.113 percent respectively. Moreover, the increase of the average Froude number of flow by 6.519, 12.787, and 26.113 percent, and average reference velocity by 13.933, 4.211, and 1.839 causes the reference design head to increase by 10, 20, and 30 percent. Whereas p-value of the profile of the flow in SPSS software is around 0.006 and very lower than 5%, it can be claimed that the numeral study is of high precision. In conclusion, the results obtained from numerical simulation have been provided and compared with the existing numerical and labora-tory studies. The accuracy of this research is describable.

Generally, spillways are provided for the storage to release excess flood water, which cannot be contained in the allotted storage space. Also, spillway weirs are used to bypass the flow released into the system like irrigation canals, power canals, feeder canals, link canals, etc. In general, the excess flow is drawn from the top of the pool created by the dam and conveyed through a nonnatural waterway, that is, a spillway, back into the same river or some other drainage channel. Due to the topography of the study area, sometimes we have to build the dam with axis arch; therefore if you use a ogee spillway in such cases, the conditions flow will change and because of this, in the dam upstream with central arc structural and hydraulic conditions are more suitable. In this study, the flow field over thw ogee spillways in axial arc condition was simulated using FLOW-3D software. In the FLOW-3D model, the Navier-Stokes and continuity equations were discretized using the finite difference method. Also, the computational domain was divided into a mesh of rectangular cells. All variables (except for velocity values) were placed at the center of the computational cells (staggered grid arrangement). To solve the governing equations, control volumes were defined around each dependent variable. The surface fluxes, body forces and surface stresses were computed in terms of surrounding variables. Most terms in the governing equations were explicitly evaluated. To solve the flow field of a non-compressible fluid, the continuity and the Navier-Stocks equations were solved. On the other hand, to validate the numerical results, the experimental measurements that were performed in Soil Conservation and Watershed Management Research Institute at reservoir with dimensions 1. 4 m length, 0. 30 m width and 0. 18 m height. The experimental model was made of plexiglas plates which was a model of prototype at the scale of 1: 75. Moreover, to measure the flow discharge, a sharp triangular weir with apex angle of 90˚ in the output of channel was used. For numerical model, the flow field turbulence was modeled using the k   standard and the RNG k   turbulence model. According to numerical model results, the k   RNG turbulence model had more accuracy than the k   standard turbulence model. Also, variations of flow free surface reconstructed using volume of fluid (VOF) scheme. Then, the effects of the side symmetrical walls of ogee spillway were examined for models 60o, 90o and 120o in discharges 34, 34 and 22. 6 lit/s, respectively. The applied boundary conditions were chosen according to the physical model. Therefore, the depth and discharge specific values were chosen for inlet boundary condition. At the outlet boundary condition, the outlet boundary condition was used. All the solid walls of the model were defined as the “ Wall” boundary condition. Also, a symmetry plane was defined at the top layer of the computation field. According to numerical results, the acceptable agreement was obtained between numerical results and experimental measurements. For example, the relative error percent of longitudinal profiles of flow free surface were computaed 12. 83, 13. 60 and 3. 48 percentage for cases 120o, 90o and 60o, respectively. Also with increasing angle of axial arc, the height of rooster tail increased significantly. In addition, by increasing Froude number, the height of rooster tail reduced.

Side weirs are flow diversion structures which have wide application in hydraulic and environmental Engineering. Diversion structures in side wall of open channel are to be used in order to divert flow from main channel. Side weirs, side orifices and side sluice gates are diversion structures which have wide application in dams, irrigation, drainage systems and combined sewer systems. Side weirs are one of the most important and applicable hydraulic structures for water controlling and directing systems that requires careful review and accurate designing due to their critical importance. In this paper, the flow over a sharp crested rectangular side weir in open channel was simulated by FLOW-3D software. RNG k-e turbulence model was used to apply the Navier-Stokes equations and the VOF method was used to model the free surface profile changes. In the present study, at first, results related to the distribution of the different components of velocity and angle of the outlet jet adjacent to the crest of the rectangular sharp crest side weir at various heights of the weir crest are validated with experimental data from Bagheri and Heidarpour (2012) research. Then the effects of upstream Froude number on flow pattern and free surface around the side weir were investigated. The results of this study indicated that with decreasing upstream Froude number the maximum and minimum longitudinal velocity along the side weir increases and decreases, respectively. By decreasing upstream Froude numbers, the longitudinal velocity in the vicinity of the side weir is negative because of the reverse flow formed in this area. The maximum lateral velocity along the side weir increased with decreasing upstream Froude number. That is why the discharge through the side weir increased with decreasing Froude number. The maximum vertical velocity along the side weir increased with decreasing the upstream Froude numbers because more flow is diverted to the side weir with decreasing the upstream Froude numbers. Distribution of the different components of velocity in the direction of flow height in the middle of the weir crest indicated that by reducing the upstream Froude number, longitudinal velocity distribution in the depth direction became more non uniform, especially near the weir crest. For different upstream Froude numbers, lateral velocity would increased up to a certain elevation from the weir crest and then decreased toward the free surface. By increasing Froude number, the maximum lateral velocity occurs at greater heights above the side weir crest. The maximum vertical velocity for different Froude numbers occurred near the weir crest. Vertical velocity gradually decreased toward the free surface. By reducing the upstream Froude number, the vertical velocity near the free surface of flow is negative due to flow motion to downward. Free surface of the flow experienced extreme changes at the end of the side weir when upstream Froude number was increasing. By increasing the Froude number, the angle of inclination of the outlet jet along the side weir increases. Also by increasing the Froude number, the separation zone around the side weir in near the main channel bed, especially in the channel cross-section decreases.

The U-shaped channels are applied as a transition cross-section from rectangular to circular in manholes.Also the U-shaped channels along the side weirs are used in the sewage networks, irrigation-drainage systems, flood protection and etc. The flow in the main channel along the side weir can be the supercritical conditions. In this study, the free surface flow in the supercritical regime has been simulated by FLOW-3D software, RNG k-e model and volume of fluid (VOF) scheme in a U-shaped channel along the side weir.The comparison between the numerical and experimental results showed that the numerical simulation predicted the free surface flow with the reasonable accuracy. Generally, the flow depth decreases with distance from the upstream end of the side weir towards the downstream end in the U-shaped channel. The APE and RMSE of the water surface profile along the side weir have been computed 1.7% and 0.213%, respectively. Also, the APE and RMSE were respectively 3.8% and 0.0177% for the discharges over the side weir. In continue, the effects of the upstream Froude number on the flow pattern in the main channel were investigated. For all Froude numbers, because of entrance effects, a free surface drop occurred at the upstream end of the side weir and the water depth gradually reduced toward the downstream end. Then, a surface jump happened at the last fourth of the side weir length in the vicinity of the inner bank. Unlike the potential energy, the kinetic energy increases along the surface jump. Also, a stagnation point is created at the end of the surface jump. The height of this stagnation point increases with increasing the Froude numbers. In addition, the dividing stream surface and stagnation zone were respectively produced near the inner and outer bank in the main channel along a side weir. The dividing stream surface reduces from channel bottom toward the side weir crest then increases to the flow surface. Also, the dimensions of the dividing stream surface and stagnation zone increased with increasing Froude number. The maximum lateral flow in the U-shaped channel occurs almost at the downstream end of the side weir. The transverse velocity increases at each cross-section of the main channel with increasing Froude number. The angle of the spilling jet (j) was close to 90o at the upstream and downstream of the side weir crest and the pattern of spilling jet angle is similar for all Froude numbers. The minimum angle of the spilling happens approximately at the downstream of the side weir crest however, the minimum j decreases with increasing Froude number. The pattern of the bed shear stress can be used to prediction of the areas of the scour and sedimentation in the alluvial channels. In the U-shaped channel along a side weir, the bed shear stress increases along the main channel axis form the beginning of the side weir toward the middle then decreases toward the downstream end. Generally, with increasing Froude number, the bed shear stress increases in the main channel along the side weir.

Peristaltic transport of an incompressible electrically conducting viscous fluid in an inclined planar asymmetric channel is studied.The asymmetry is produced by choosing the peristaltic wave train on the walls to have different amplitude and phase. The closed form solutions of momentum and energy equation in presence of viscous dissipation term are obtained for long wave length and low Reynolds number approximations.The effects of different parameters entering into the problem are discussed numerically and explained graphically.

Conventional ships have been used for many years with usual body forms. But recent developments in high speed crafts have created many different alternatives. Therefore the selection of hull type becomes an important issue in the preliminary design stage. This selection should be based on performance comparisons and also other parameters such as building costs. Since planing monohulls and catamarans are very popular types of high speed crafts, in this paper their behaviors from resistance at high speeds are compared. The results may prove useful for designers at conceptual or preliminary design stages.

In this study, horizontal screens were used in the edge of vertical drops, as an excessive energy dissipater of flow, to increase dissipation of energy in vertical drops with the supercritical flow at upstream. Experiments adjusted for a simple vertical drop and a drop equipped by screens with two porosity values and three openings of the upstream sluice gate. During the experiments, it was observed that the horizontal screen after drop increased the air entrance and turbulence in the pool due to dividing the falling jet into a large number of small vertical jets. The results indicate that using these plates in the vertical drops increases the relative depth of downstream, relative depth of pool and relative energy dissipation as compared to a simple vertical drop. Also, results showed by increasing the upstream Froude number and decreasing the relative critical depth, the relative energy dissipation increases. However, the porosity of screens has not a significant effect on energy dissipation. Investigation and comparison of the results corresponded to the simple vertical drops and the ones equipped with screens indicated that incorporating the horizontal screens in these structures eliminate or decrease the length of stilling ponds.