ESEL Paper Review_20130309

By Hong Guo

Mail: hongguo@gist.ac.kr

Phone: (+82) (0)10 82276568

1, Title and Author

Title: Modeling Particulate Matter Resuspension and Washout from Urban Drainage Hydrodynamic Separators

Journal: Journal of Environmental Engineering

Authors:

Subbu-Srikanth Pathapati1 and John J. Sansalone, M.ASCE2

1 Postdoctoral Researcher, Environmental Engineering Sciences, Univ. Of Florida, Engineering School of sustainable Infrastructure and Environment (ESSIE), 220 Black Hall, Gainesvile, FL 32611. Email: spatha1@ufl.edu

2 Professor, Environmental Engineering Sciences, Univ. Of Florida, Engineering School of sustainable Infrastructure and Environment (ESSIE), 220 Black Hall, Gainesvile, FL 32611. Email: Jsansal@ufl.edu

2. Summary of Paper

This study combines physical and computational fluid dynamics (CFD) models to quantify washout from two common HS types: screened (SHS) and baffled (BHS). Washout of particles size distributions (PSDs) for a range of flows is examined. Trajectory analysis of particulate matter (PM) illustrates entrainment and washout as a function of PSDs and PM deposit depth. Velocity distributions identify washout-critical PM sizes and areas. Bed profiles are modeled by integrating velocity distributions across washout areas. The physically validated CFD model reproduces washout as a function disperse PSD. In this paper the authors hypothesized that the scale and complexity of washout in unit operations such as an HS can be quantified by a physically validated computational fluid dynamics (CFD)

3. Results

? CFD results are examined on the basis of fluid velocities and path lines, velocity vectors, isosurfaces of velocities, and normalized frequency distributions.

? A larger fraction of the fluid volume is mobilized in the screened hydraulic separator (HS) compared to the baffled HS.

? The bottom region of the screened HS has higher flow velocity magnitudes as compared to the baffled HS. The lower zone of the baffled HS is predominantly quiescent without volumetric utilization.

? The volute area, with a narrow distribution of lower velocities, is more conducive to discrete particle settling and to washout.

? The wahout from the baffled HS is influenced by the PSD of the settled PM. There also is an increase in washout as flow rate increases from 100% (9L/s) to 125 (11.3 L/s) of design flow rate.

? Relative percent differences are utilized to compare measured and CFD modeled results , and are calculated. The CFD model is able to reproduce measured results, with all RPDs below 10%.

? The shape of washout on the basis of velocities is predicted by integrating across the depth of the area of the deposited PM surfaces.

? Fig. 8 illustrates fairly uniform velocity distributions in the baffled HS that do not translate to a predominance of washout in any given region. There is a slight peak corresponding to the baffled HS area directly below the effluent drop-pipe, suggesting washout potential directly underneath.

4. Contribution:

The author completed the work to examine washout from two common hydrodynamic separators for two PSDs fo predeposited PM, across a range of flow rate. The paper shows the many knowledge to do the CFD model work’ field. The precious knowledge from this books could be applied in our lab’s future works (Particle tracing model)

5. Author information:

Email: andy.chan@nottingham.edu.my