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Research Interests

-   Description of extreme flow events in hydraulic systems

Experimental and numerical investigations on the rapid filling pipe problem, focusing on surges, waterhammer and air-water interactions during filling events. Applications on extreme inflows experienced by deep stormwater storage tunnels and refilling operations in pipelines. We are particularly interested in cases when air-water flow interactions play an important part in the dynamics of the filling process.

Figure 1 - Interface breakdown phenomena caused by air pressurization during rapid filling of closed pipes

Figure 2 - Major geyser on a highway event likely to be linked to air-water interactions

-   Modeling of the transition between pressurized and free surface flows

Investigation on alternatives to account in a single modeling framework the ability to simulate both pressurized and free surface flows, referred to either as Flow Regime Transition or Mixed Flows. Development of the Two-component Pressure Approach (TPA) model and variants to modify the St. Venant equations to enable those to simulate pressurized flows. Study on the nature of numerical solutions involving mixed flows, including post-shock oscillations. Our work have yielded versions of the TPA model that are apt to simulate distributed cavitation, air pocket compression and expansion, as well to detect the entrapment of air pockets during the filling process.

Figure 3 - Comparison between TPA model and the traditional Preissmann slot model to simulate flow regime transition (aka mixed flows) in closed pipelines

-   Watershed hydrology monitoring and modeling

Investigations involving field and numerical modeling of surface-groundwater processes in the headwaters of watershed, including effects of highway traffic and rapid changes in water quality parameters. Tools that we have been using include EPA SWMM5 and GSSHA.

-   Sediment-laden multiphase flows representation in construction site runoff 

Investigations to improve effectiveness of sediment capture in sediment basins in construction sites, involving large scale testing and CFD modeling. Our work have now included the mechanisms for resuspension of sediments in construction site sediment basins, and developing countermeasures to such occurrences.

-   Stormwater modeling and optimization

We are interested in applications that involve improving the accuracy of stormwate modeling, as well cost optimization of these systems. Research has been focused in developing user-friendly tools to aid in these tasks for various types of stormwater management practices.

-   Study of Gravity Currents

Experimental and numerical investigations of gravity currents, assessment of during the advance of salinity-driven currents and for stratified flows. Use of shallow water equation models to quickly simulate the advance of gravity currents.

Figure 4 - Top: Advance of a gravity current (GC) on the experimental apparatus developed to study mixing on the Mobile Bay navigation channel. Bottom: modeling of GC flows using SWE models based on Finite Volume and Riemann solvers and a comparison with the EFDC result. We are also applying OpenFOAM to simulate these types of flows