5267

4937

كارشناسي ارشد

آبياري و زهكشي

اصفهان: دانشگاه صنعتي اصفهان، دانشكده كشاورزي

1388

نه،131ص.:مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

منوچهر حيدرپور،اسماعيل لندي

سيدحسن طباطبائي

22/3/89

جهانگير عابدي كوپايي،محمدرضا مصدقي

مهندسي كشاورزي

ID4937

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

The Effect of Vegetation on Dispersion Coefficient of Pollution in a Rectangular Channel Pooya Shirazi p shirazi@ec iut ac ir Date of Submission 2010 06 14 Department of Water Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Manouchehr Heidarpour heidar@cc iut ac ir Esmaeil Landi Abstract Vegetation is ubiquitous in rivers estuaries and wetlands strongly influencing both water conveyance and mass transport The plant canopy affects both mean and turbulent flow structure and thus both advection and dispersion The stream transfer and mass transfer strongly influenced by vegetation in rivers canals and wetlands Vegetation influences the amount of flow and turbulent flow structure and thus the processes of transmission and dispersion are also affected The aim of this study is evaluating the effect of vegetation on the lateral mixing coefficient and variations of flow structure in the presence of vegetation with different densities Detection and velocity estimation experiments in two laboratory rectangular Flume the first has 7 meters length 0 32 meters width and 0 35 meters height at Isfahan University of Technology and the second has 20 meters length 0 6 meters width and 0 6 meters height at Shahr e kord University was performed Experiments were conducted in two parts 1 first part was conducted in 0 32 meter Flume to evaluate the effect of vegetation density on the transverse mixing coefficient Here woody cylinders with 6 mm diameter and height of 130 mm was used to simulate vegetation and was installed in flume floor at four different densities 2 Second Part was conducted in 0 6 meter Flume to evaluate the effect of aspect ratio on the coefficient of lateral mixing in the presence of vegetation in this part Wheat clusters of the average height of 120 mm used as the vegetation Mecanol of diluted sodium chloride with specified concentration used as the tracer substance In the downstream of injection site Concentrations at 4 sections and 15 points in each section were measured Transverse mixing coefficient using the simplified relations of conservation of mass equation in different densities and different ratios of width to depths were calculated Since 3 dimentional ADV was used to measure the speed the velocity distribution Reynolds stresses and turbulence intensity for all of the cases studied Results showed that the transition and mass transfer mechanism between the free zone and area of vegetation affect the process of dispersing tracer substance and the initial control is carried out by the density of vegetation up to a certain density of vegetation With increasing density of vegetation the length of the region which secondary streams occur in is decreasing and thus mixing process is reducing But with more increased density of vegetation there is no linear relationship between vegetation density and length of the region which secondary streams occur in and flow mixing process is increased assuming constant channel width increasing the width to depth ratio length of the region which secondary streams occur in is reducing and thus the process of mixing and cross mixing coefficients are also reduceding Keywords Transverse Mixing Coefficient Density of Vegetation Secondary Current Aspect Ratio Intensity Turbulance

منوچهر حيدرپور،اسماعيل لندي

سيدحسن طباطبائي

جهانگير عابدي كوپايي،محمدرضا مصدقي