Scour Analysis in High Vertical Drop Shallow Using Numerical and Physical Models
The "vertical drop Structure" is one of the basic types used in channel system flow. Drops are used as slope breakers in some parts of channels where we encounter supercritical slopes. Scour is a dynamic phenomenon that is visible in vertical drop tail water depth. Because of complexity of Scour process and simultaneous testing of variables' effective compliance, studies are still underway to determine the accuracy of the equations and provide possible explanation for this phenomenon. These investigations include field or laboratory experiments under special conditions where mathematical models have been often used to provide an explicit result. Using the laboratorial physical modeling, this research explores the impact of a vertical drop flow rate on the balance of forces at the scour depth below a high vertical drop . Satisparametery results have been obtained by changing several of the parameters like sediments grading, tail water depth and flow rate. In order to specify a set of effective parameters, dimensional analysis has been used to show the scour hole dimensions. Also, computer software FLOW-3D was used to simulate the numerical modeling of Scour below a high vertical drop. The data from numerical simulation is then compared with physical modeling resulting in the great compatibility and correlation.
Scour below a high vertical drop
Experimental results on scour below a high vertical drop (drop height/critical depth >1) in uniform sands and gravels are presented. The experimental results are used to describe the effects of important parameters, identified from the dimensional analysis, on equilibrium scour depth. The important observations are that the equilibrium scour depth increases with increase in densimetric Froude number, whereas the scour depth decreases with increase in sediment size and tailwater depth. The time scale of scour depth that follows an exponential law is determined. The nondimensional time scale decreases with increase in densimetric Froude number.
Monte carlo simulation of events with Drell-Yan lepton pairs from antiproton-proton collisions
The complete knowledge of the nucleon spin structure at leading twist requires also addressing the transverse spin distribution of quarks, or transversity, which is yet unexplored because of its chiral-odd nature. Transversity can be best extracted from single-spin asymmetries in fully polarized Drell-Yan processes with antiprotons, where valence contributions are involved anyway. Alternatively, in single-polarized Drell-Yan the transversity happens convoluted with another chiral-odd function, which is likely to be responsible for the well known (and yet unexplained) violation of the Lam-Tung sum rule in the corresponding unpolarized cross section. We present Monte Carlo simulations for the unpolarized and single-polarized Drell-Yan pp{sup ({up_arrow}}{sup )}{yields}{mu}{sup +}{mu}{sup -}X at different center-of-mass energies in both configurations where the antiproton beam hits a fixed proton target or it collides on another proton beam. The goal is to estimate the minimum number of events needed to extract the above chiral-odd distributions from future measurements at the high energy storage ring (HESR) at GSI. It is important to study the feasibility of such experiments at HESR in order to demonstrate that interesting spin physics can be explored already using unpolarized antiprotons.