scholarly journals Investigation of the Turbulent Schmidt Number Effects On Numerical Modelling Of Vortex-Type Stormwater Retention Ponds

2021 ◽  
Author(s):  
S. M. Yamini ◽  
H. Shamloo ◽  
S. H. Ghafari
Keyword(s):  
Numerical Modelling ◽  
Schmidt Number ◽  
Retention Ponds ◽  
Turbulent Schmidt Number ◽  
Stormwater Retention

Analysis of the Mixing and Emission Characteristics in a Model Combustor

2018 ◽  
Author(s):  
Shan Li ◽  
Shanshan Zhang ◽  
Lingyun Hou ◽  
Zhuyin Ren
Keyword(s):  
Gas Turbines ◽  
Schmidt Number ◽  
Numerical Study ◽  
Flame Temperature ◽  
Scalar Dissipation ◽  
Mixing Process ◽  
Nox Formation ◽  
Turbulent Schmidt Number ◽  
Wide Range ◽  
Air Mixing

Modern gas turbines in power systems employ lean premixed combustion to lower flame temperature and thus achieve low NOx emissions. The fuel/air mixing process and its impacts on emissions are of paramount importance to combustor performance. In this study, the mixing process in a methane-fired model combustor was studied through an integrated experimental and numerical study. The experimental results show that at the dump location, the time-averaged fuel/air unmixedness is less than 10% over a wide range of testing conditions, demonstrating the good mixing performance of the specific premixer on the time-averaged level. A study of the effects of turbulent Schmidt number on the unmixedness prediction shows that for the complex flow field involved, it is challenging for Reynolds-Averaged Navier-Stokes (RANS) simulations with constant turbulent Schmidt number to accurately predict the mixing process throughout the combustor. Further analysis reveals that the production and scalar dissipation are the key physical processes controlling the fuel/air mixing. Finally, the NOx formation in this model combustor was analyzed and modelled through a flamelet-based approach, in which NOx formation is characterized through flame-front NOx and its post-flame formation rate obtained from one-dimensional laminar premixed flames. The effect of fuel/air unmixedness on NOx formation is accounted for through the presumed probability density functions (PDF) of mixture fraction. Results show that the measured NOx in the model combustor are bounded by the model predictions with the fuel/air unmixedness being 3% and 5% of the maximum unmixedness. In the context of RANS, the accuracy in NOx prediction depends on the unmixedness prediction which is sensitive to turbulent Schmidt number.

scholarly journals Gas-solid and gas-liquid mass transfer: Effect of turbulent Schmidt number

2007 ◽  
Vol 13 (3) ◽  
pp. 167-168 ◽  
Author(s):  
Aleksandar Dudukovic ◽  
Rada Pjanovic
Keyword(s):  
Mass Transfer ◽  
Eddy Viscosity ◽  
Schmidt Number ◽  
Mass Transfer Rate ◽  
Transfer Effect ◽  
Transfer Coefficients ◽  
Mass Transfer Effect ◽  
Liquid Mass ◽  
Turbulent Schmidt Number ◽  
Liquid Mass Transfer

The scope of this paper is to explain effect of eddy viscosity and turbulent Schmidt number on mass transfer rate. New, theoretically based correlation for gas-liquid mass transfer coefficients are proposed.

scholarly journals Sorption and Degradation Potential of Pharmaceuticals in Sediments from a Stormwater Retention Pond

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 526 ◽  
Author(s):  
Fan Liu ◽  
Asbjørn Nielsen ◽  
Jes Vollertsen
Keyword(s):  
Half Life ◽  
Pond Water ◽  
Organic Micropollutants ◽  
Partitioning Coefficient ◽  
Retention Pond ◽  
Retention Ponds ◽  
Water Partitioning ◽  
Stormwater Retention ◽  
Sorption Potential

Stormwater retention ponds commonly receive some wastewater through misconnections, sewer leaks, and sewer overloads, all of which leads to unintended loads of organic micropollutants, including pharmaceuticals. This study explores the role of pond sediment in removing pharmaceuticals (naproxen, carbamazepine, sulfamethoxazole, furosemide, and fenofibrate). It quantifies their sorption potential to the sediments and how it depends on pH. Then it addresses the degradability of the pharmaceuticals in microcosms holding sediment beds and pond water. The sediment-water partitioning coefficient of fenofibrate varied little with pH and was the highest (average log Kd: 4.42 L kg−1). Sulfamethoxazole had the lowest (average log Kd: 0.80 L kg−1), varying unsystematically with pH. The coefficients of naproxen, furosemide and carbamazepine were in between. The degradation by the sediments was most pronounced for sulfamethoxazole, followed by naproxen, fenofibrate, furosemide, and carbamazepine. The first three were all removed from the water phase with half-life of 2–8 days. Over the 38 days the experiment lasted, they were all degraded to near completion. The latter two were more resistant, with half-lives between 1 and 2 months. Overall, the study indicated that stormwater retention ponds have the potential to remove some but not all pharmaceuticals contained in wastewater contributions.

Free Turbulent Shear Layers on Plug Nozzles

1977 ◽  
Vol 99 (2) ◽  
pp. 301-308
Author(s):  
C. J. Scott ◽  
D. R. Rask
Keyword(s):  
Turbulent Mixing ◽  
Schmidt Number ◽  
Error Function ◽  
Mixing Layer ◽  
Shear Layers ◽  
Turbulent Shear ◽  
Gas Chromatograph ◽  
Plug Nozzle ◽  
Turbulent Schmidt Number ◽  
Plug Nozzles

Two-dimensional, free, turbulent mixing between a uniform stream and a cavity flow is investigated experimentally in a plug nozzle, a geometry that generates idealized mixing layer conditions. Upstream viscous layer effects are minimized through the use of a sharp-expansion plug nozzle. Experimental velocity profiles exhibit close agreement with both similarity analyses and with error function predictions. Refrigerant-12 was injected into the cavity and concentration profiles were obtained using a gas chromatograph. Spreading factors for momentum and mass were determined. Two methods are presented to determine the average turbulent Schmidt number. The relation Sct = Sc is suggested by the data for Sc < 2.0.

scholarly journals Microplastics in urban and highway stormwater retention ponds

2019 ◽  
Vol 671 ◽  
pp. 992-1000 ◽  
Author(s):  
Fan Liu ◽  
Kristina Borg Olesen ◽  
Amelia Reimer Borregaard ◽  
Jes Vollertsen
Keyword(s):  
Retention Ponds ◽  
Stormwater Retention

scholarly journals On the Values for the Turbulent Schmidt Number in Environmental Flows

Fluids ◽  
2017 ◽  
Vol 2 (2) ◽  
pp. 17 ◽  
Author(s):  
Carlo Gualtieri ◽  
Athanasios Angeloudis ◽  
Fabian Bombardelli ◽  
Sanjeev Jha ◽  
Thorsten Stoesser
Keyword(s):  
Schmidt Number ◽  
Environmental Flows ◽  
Turbulent Schmidt Number
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