Abstract:The depth-duration-frequency curves and isopluvial maps for the region encompassing South Carolina, North Carolina, and Georgia were developed using the available rainfall data. The aim was to update the existing intensity-duration-frequency curves in the region and obtain these curves at ungauged sites throughout the region using the newly developed rainfall frequency analysis techniques. A total of 17 durations ranging from 15 minutes to 120 hours for return periods of 2, 10, 25, 50, and 100 years were analyzed. The L-moment method with X-10 test was used to search for homogeneous regions within the study area. It was found that the method was either unable to homogeneous regions that were geographically contiguous or too many stations had to be eliminated before a region could be considered homogenous. Finally, at-site statistics were calculated to develop frequency relationships. Normal, lognormal, generalized extreme value, Pearson type III, and log Pearson type III probability distribution functions were used to fit the maximum annual precipitation data at each gauging site for each duration. The chi-squared goodness-of-fit test was used to determine the best fit probability distribution. The new intensity-duration-frequency curves were found to be lower than the existing curves developed in 1986. The difference between the two set of curves was found to be due to the removal of the outliers in the present study and the existence of the post 1986 drought conditions in the region. The spatial interpolation of the rainfall intensity from the depthduration-frequency curves was found to yield accurate intensity-duration-frequency curves and could be used to develop these curves at ungauged sites in the study area.
In this study, plane and circular turbulent non-buoyant jets are simulated numerically using a threedimensional computational model. The aim of the study is to evaluate the accuracy of turbulent closure schemes employed in three-dimensional models. In particular, standard k−ε and renormalized group k−ε schemes with standard coefficients are evaluated. The modeled jets are deeply submerged, that is the impact of free surface and solid boundaries on jets are eliminated. The accuracy of the turbulent schemes is assessed by analyzing the decay of centerline velocity, jet growth rates, similarity of longitudinal and vertical velocity profiles, and turbulent kinetic energy profiles. The results from the two turbulent closure schemes are compared with accepted experimental and theoretical studies to determine their accuracy. It is found that the k−ε scheme with standard coefficient performs equally well and in some cases better than the renormalized group k−ε scheme. Finally, the model is applied to analyze flow pattern in the Sampit River, South Caroline, USA, resulting from stormwater discharge in a recreational area. Various inlet designs are investigated and box inlet is found to provide a practical means of localizing high surface currents.
In this paper, a submerged hydraulic jump is modelled using k–ε and renormalisation group (RNG) turbulent schemes with standard coefficients. The computed results of mean and turbulent flow properties for three different cases of inlet Froude number and submergence ratio are compared with the measured data. The results show that the longitudinal velocity profile and its maximum value in the vertical direction are estimated better by the RNG model. Both schemes overpredict the water surface level within the recirculation zone for higher Froude numbers. The longitudinal velocities in the shear layer near the inlet are overpredicted by the two schemes. The longitudinal extent and the magnitude of reverse velocities are predicted well by both schemes. The vertical profiles of kinetic energy per unit mass are predicted well away from the inlet. Near the inlet the trends are predicted well; however, both the magnitude and the height above the bed at which the maximum kinetic energy occurs are overpredicted. The three-dimensional nature of the flow, especially near the inlet is also shown.
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