الفهرس 
Chapter (1) IntroductionOnly 14 pages are availabe for public view
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Abstract
The present study highlights the effect of transport of cohesive soil on the velocity distributions in the three dimensional co-ordinates using Acoustic Doppler Velocimeter (ADV) instrument for measuring velocities. A complete tilting circular channel has been designed, to mimic the wastewater flow in sewer pipe, having a diameter of 200 mm, in the hydraulic laboratory at the faculty of engineering Mansoura University. The factors that affect the wastewater flow characteristics through a circular pipe namely concentration of suspended solids, concentration of both suspended solids and scum and temperature degree have been demonstrated. Comparison between characteristics of wastewater flow velocities for different concentrations of clay and scum and also the corresponding clear water has been given. A system of design curves and equations has been presented. These curves give the relationships between the relative water depth and the corresponding relative water velocity for different degree of clay concentration as well as the scum concentration. It was found that for clear water the relationship between relative water depth and the corresponding relative velocity has a logarithmic function. In colloidal water, water contains clay or clay and scum, the relationship between relative water depth and relative velocity has a polynomial function from the second degree. The polynomial function coefficients depend on water discharge, the degree of concentration for both clay and scum and temperature degree. The experimental work highlighted that there is a maximum value of concentration at which the suspended sediment begins to settle as a bed load this value is known as a critical value of concentration and the corresponding velocity is known as the critical velocity. For each circular section there exist critical mean velocity that can transport a critical concentration of cohesive soil mixed with the stream. At the critical conditions of the soil concentration and mean velocity, the velocity of the bottom layer is zero. At 18o C and for 5 gm/lit clay concentration, the reduction in relative velocity in comparison with clear water could reach 19%.Comparison between clear water and 5 gm/lit clay concentration in addition to 6 gm /lit scum could decrease the relative velocity by about 28.3%.Decreasing discharge from 1.5 lit/sec to 1.07 lit/sec for 5 gm/lit clay and 6 gm/lit scum concentrations could decrease the relative velocity by 27.8%, at 18o C. Decrease of wastewater temperature from 18º C to 9º C has shown a tremendous effect on the velocity distribution for example the reduction in relative velocity may reach to 21 % at discharge of 1.5 lit/sec. Based on the critical shear stress the self-cleansing velocity value depends on the median particle of the transported sediment load. Increasing the particle size increases the values of critical shear stress and self-cleansing velocity.