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Published on: May 22, 2020
Discrete phase model representation of particulate matter (PM) for simulating PM separation by hydrodynamic unit
Joshua A Dickenson1, John J Sansalone
1Environmental Engineering and Sciences, University of Florida, Gainesville, Florida 32611, USA. jd83@ufl.edu
Environmental Science & Technology
|November 21, 2009
Summary
Discrete phase modeling (DPM) and computational fluid dynamics (CFD) accurately predict particulate matter (PM) fate in hydrodynamic separators. Model accuracy depends on particle size distribution (PSD) and discretization number (DN), with DN 16 sufficient for heterodisperse PSDs.
Area of Science:
- Environmental Engineering
- Fluid Dynamics
- Particle Science
Background:
- Modeling particulate matter (PM) separation in rainfall-runoff clarification is crucial.
- Historical models often used simplified PM representations (lumped gravimetric index), lacking particle-specific fate information.
- Accurate PM representation and separation mechanisms remain a challenge in treatment unit operations.
Purpose of the Study:
- To apply discrete phase modeling (DPM) and computational fluid dynamics (CFD) for modeling PM fate in hydrodynamic separators (HS).
- To investigate the influence of particle size distribution (PSD) and flow rate on PM separation.
- To determine discretization requirements (DN) for accurate modeling of various PSDs.
Main Methods:
- Utilized computational fluid dynamics (CFD) coupled with discrete phase modeling (DPM).
- Simulated PM fate in two common hydrodynamic separator (HS) types.
- Analyzed particle size distributions (PSDs) ranging from heterodisperse to monodisperse, assessing discretization number (DN) and associated errors.
Main Results:
- Accurate prediction of heterodisperse PSD fate was achieved with a discretization number (DN) of 16.
- The study quantified the impact of size dispersivity and PM fineness on DN requirements.
- Using a single particle size index (e.g., d(50m)) is accurate only for monodisperse PSDs.
Conclusions:
- CFD-DPM provides a robust method for modeling PM fate in HS units.
- Discretization number (DN) is critical for accurately representing PSDs in simulations.
- The findings highlight the limitations of simplified PM indices for complex PSDs.
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