Jungseok Ho

Case Study: Movable Bed Model Scaling for Bed Load Sediment Exclusion at Intake Structure on Rio Grande

Results of a laboratory modeling study are presented for excluding bed load sediment from a diversion/intake structure on the Rio Grande in Albuquerque, New Mexico. To achieve model similitude, crushed coal was used to model the prototype sediment in a 1:24 scaled model with an exaggerated slope such that shear force is adequately modeled. The Shields parameters and critical Shields parameters were matched between the prototype and the model, resulting in similar grain Reynolds numbers. Twenty-four tests, where guiding walls, submerged vanes, and/or the angle of the intake bay were altered, were conducted for a single river and diversion flow rate to develop the best performing sediment exclusion system at the intake structure. Independent vanes with 45° rotated intake bays were recommended for the most effective sediment exclusion at the intake structure.

Numerical Modeling Study for Fish Screen at River Intake Channel

A numerical modeling study of hydraulic performances of an angled vertical fish screen at a river diversion intake channel that was developed using a porous media numerical scheme. Flow patterns in the intake channel induced by the fish screen were computed with a three-dimensional fluid dynamics computation program solving the Reynolds-averaged Navier-Stokes equations. Screen flow head loss coefficient were simulated and compared with the physical model values converted from the test measurements for the porous media numerical scheme applicability test. For validation of the numerical model, fish screen velocity ratio profiles of sweeping and approach were compared with physical model measurements. Different types of screen face material and baffle installations for uniform approach flow distributions were simulated. The numerical model shows very good agreement with the velocity ratio measurements, and modeling capability for different screen material types and baffle installations by controlling of the numerical model of the porous opening directions and adjustment of baffle porosities respectively.

Flood debris filtering structure for urban storm water treatment

A simple and effective debris removal structure, the Drop Flow Debris Filter, is developed for urban storm water channels as a best management practice. This structure consists of two almost horizontal, slightly sloped plates, one placed above the other to form a debris basin. This system allows storm water to exit through the bottom of the debris basin, while floating and heavy debris are retained in the basin. A 1 : 12 scale physical model in a flume and a three-dimensional computational fluid dynamics model were used to investigate the debris-filtering performance of the system. To achieve enhanced debris filtering, a horizontal ramp was added to the preliminary model and both plates were curved. The curved plates model showed the most successful debris filtering performance by providing a compact short-circulation zone of water with reduced separation length and increased energy loss.

Experimental Study to Parameterize Salt-Wedge Formations in Coastal Aquifer

Saltwater intrusion in coastal aquifer was investigated using a laboratory model. Salt-wedge profiles were reproduced in a porous media tank 140 cm long, 70 cm high, and 10 cm wide. The experiments were performed with various conditions of porous media hydraulic conductivity, salinity, and ground surface slope to assess relationships on salt wedge location and inclination. Salt-wedge profiles induced by saltwater intrusion were observed in porous media equilibrium state, and compared with previously derived formulas of the Glover (1959), Henry (1959) and Strack (1976). It was found that salt-wedge shape and formations were affected by the water level ratio () due to high hydraulic conductivity, saltwater salinity and ground surface slope. High of porous media having high hydraulic conductivity shifted the saltwater interface toward the saltwater reservoir. Increasing surface slope of the porous media caused the salt-wedge profile inclination to decrease. Saltwater salinity also contributed to the location of saltwater interface, yet the impact was not more significant than hydraulic conductivity.

Storm Water Best Management Practice: Development of Debris Filtering Structure for Supercritical Flow

A simple, but effective, debris removal structure was developed for supercritical flow in urban storm water channels. This structure was designed as a best management practice in response to the National Pollution Discharge Elimination System. The Drop Flow Debris Filter (DFDF) structure consists of two slightly sloped plates, one placed above the other to form a debris basin. The DFDF structure translates supercritical flow of the storm water channel into subcritical flow in the debris basin. This system creates flow paths that only allow water in the bottom of the basin to pass through while debris is retained in the upper part of the basin. To investigate the hydraulic performance of the DFDF structure, a 1:3 scale undistorted physical model was constructed in a 0.91 m wide plexiglass flume. This model was also created in a three-dimensional computational fluid dynamics program. Three different density spheres were used in this model study to reproduce different buoyant storm water debris. Six different DFDF designs were developed and tested, and the modified curved plates design was recommended for the best performing DFDF structure.

Hydraulic Modeling Study for Rio Grande Diversion Structure at Albuquerque

Hydraulic model tests of flow properties of diversion structure gates are presented for the proposed diversion structure on the Rio Grande at Albuquerque, New Mexico. The Rio Grande diversion structure is composed of independently controlled adjustable height gates across the channel, a fish passage through the diversion structure, and an intake channel for 3.7 m 3 /s of maximum river diversion. A 1:24 scale distorted movable bed hydraulic physical model was constructed at the Water Resources Research Laboratory of U.S. Bureau of Reclamation in Denver, Colorado. The hydraulic performances of the diversion structure that were tested include the gates operation over various flow rates, flow transitions and sediment exclusions at the intake channel. Two-dimensional hydrodynamic numerical model was built to simulate the flow properties around the diversion structure. Velocity vector computations around the intake structure and the diversion gate openings are compared with the physical test measurements. The numerical model shows very good agreements with the physical model measurements.