Sharif Digital Repository

In this study amount of soil erosion in watershed of JAJROOD is estimated by use of the RULSE model with the help of GIS12. JAJROOD River is located in upstream of LATIAN Dam and is one of the most important water sources of Tehran. Also, this River has a big role in preventing the flood. modeling Results show that the amount of soil erosion is high due to high slope of the land, lack of plant coverage and the quality of soil and changing the land application, lead to increase in erosion potential. modeling Results have estimated the amount of erosion in this basin about 1,524,511 tons in a year. In order to evaluate Results and efficiency of the model, all of obtained results are compared... 

Wall thickness measurement and deterioration determination of 6 and 10 inch pipes due to corrosion/erosion/pitting was evaluated by using radiographic film density measurements. Special reference blocks were prepared with defined step wall reductions and artificial defects. Gamma radiography with a Ir-192 source was used. A double-wall technique with longitudinal film arrangement was used for this purpose. Formulae were developed from the experiments for numerical calculations. It was observed that this method can determine remaining wall thickness as well as pitting corrosion in insulated and non-insulated pipes with differential and absolute density measurements. The purpose of the work... 

This study investigates critical run-off and sediment production sources in a forested Kasilian watershed located in northern Iran. The Water Erosion Prediction Project (WEPP) watershed model was set up to simulate the run-off and sediment yields. WEPP was calibrated and validated against measured rainfall-run-off-sediment data. Results showed that simulated run-off and sediment yields of the watershed were in agreement with the measured data for the calibration and validation periods. While low and medium values of run-off and sediment yields were adequately simulated by the WEPP model, high run-off and sediment yield values were underestimated. Performance of the model was evaluated as... 

Erosive wear is one of the efficiency reduction causes in centrifugal compressors. The presence of suspended solid particles in the fluid causes deformations in different parts of the compressor, especially blades of the impeller. Therefore, erosion not only decreases the part lifetime by destruction of blades form, but also increases energy losses. For this reason, specifying the erosion locations and choosing a suitable material have an important effect on optimum functionality of the machine. In this paper, erosion locations of a compressor impeller by using computational fluid dynamics (CFD) in high temperature and pressure are attained and compared with experimental model. The... 

In this paper, the structure of a wall jet deflected by a baffle along with the trajectory of particles has been studied. This baffle is used to produce a stable deflected surface jet, thereby deflecting the high-velocity supercritical stream away from the bed to the surface. An elliptic relaxation turbulence model (v2̄ - f model) has been used to simulate this submerged flow. During the last few years, the v2̄ - f turbulence model has become increasingly popular due to its ability to account for near-wall damping without use of damping functions. In addition, it has been proven that the v2̄ - f model is superior to other RANS methods in many fluid flows where complex flow features are... 

The present study investigates the dynamic filtration of concentrated slurry fluids containing colloidal clay particles under different salinity, shear flow, and flux rate conditions. The dynamic filtration study was carried out by the filtration cell equipped with a rotating disk to apply shear stress over the membrane surface. A 3D CFD simulation has been implemented to model the hydrodynamic flows inside the filtration cell to obtain the wall shear stress (WSS) on the membrane surface at different disk rotation speeds. The thickness and surface patterns of fouling were captured utilizing a surface profilometer. First, the cake-filtration model was used to predict the flux rate and fouling... 

In this study, effects of tungsten on wear resistance of high chromium white cast iron with and without tungsten in erosion-corrosion condition have been investigated. At the same time, the comparison between wear resistance of this grade of cast iron and low alloy steels with various contents of Cr which are used in industrial condition (in Sarcheshme Company, the greatest copper production company in the Middle East and with more than 4000 years historical cupper production background) was studied, while, copper concentrates have used for erosion particles. Results show that, because of higher hardness of matrix due to the tungsten, the wear resistance of high chromium cast iron increases.... 

This paper introduces the concept of a submerged hydraulic jump being used for energy dissipation. A baffle wall is used to produce a stable deflected surface jet, thereby deflecting the high-velocity supercritical stream away from the bed to the surface. An elliptic relaxation turbulence model (v 2̄ - f model) has been used to simulate this submerged flow. During the last few years, the v2̄ - f turbulence model has become increasingly popular due to its ability to account for near-wall damping without use of damping functions. In addition, it has been proved that the v̄2 - f model is superior to other RANS methods in many fluid flows where complex flow features are present. In this study,... 

In this paper, the internal ballistics of solid propellant rocket motor with an arbitrary grain configuration is numerically investigated using quasi one dimensional simulation of Inviscid conservation equations. The upwind Roe's scheme is used to calculate the convective fluxes. Appropriate burning rate model to predict the erosive burning in solid propellant is used here. By using this phenomenon and accurate simulation, tactical motor performance can be considerably improved  

The present study examined the effect of nanoparticle size and geometry on filter cake buildup during dynamic filtration using experimental and modeling approaches. A dynamic filtration setup was proposed and designed to test cross-flow circulation against a synthetic core at a constant differential pressure. The proposed mathematical model considers the critical deposition boundary of the porous media for particles along with drag, lift, friction, buoyancy, permeate, and electrostatic forces. The comprehensive model response allowed investigation of the aggregation and shape of nanoparticles at different cross-flow inclinations. The drag and lift force coefficients and moment of inertia of... 

Whole level of the erosion and the resistance of rocks which were composed closured have been studied, besides, the impact of temperature and laser irradiation for more investigation about this issue has been involved before all. This subject more reveals the matter which laser absorption on the laboratory scale using laser to what extent can cause the augment of the relative permeability and secondary porosity of reservoir rock, that of the vertical and horizontal useful connectivity and eventually that of the positive transferability. This research has been carried out in the form of case study on one of Iranian south west formations in north east of Behbahan city in Iran, either the rate... 

Mechanical failure of materials adjacent to the production cavity and material disaggregation caused by fluid drag are considered as the most important parameters that affect sand production. In light of such factors, the coupling of two mechanisms-mechanical instability and hydrodynamic erosion-is indispensable in order to model this phenomenon successfully. This paper examines the applicability of a coupled hydro-mechanical erosion criterion for simulating sand production using the finite element method. The porous medium was considered fully saturated. The onset of sanding and production of sand were predicted by coupling mechanical failure and subsequent erosion of the grain particles...