• Ocean and Polar Research
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• v.22 no.1
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• pp.45-56
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• 2000

Hydrodynamic mixing characteristics of submerged effluent discharges into Masan Bay were investigated by both field observations and numerical model simulations. CORMIX model, a length-scale mixing model, was adopted to obtain the near-field dilution and wastefield characteristics of the effluent discharges into Masan Bay. Model predictions of the near-field dilution rates were in a good agreement with field observations in summer and winter seasons. Seasonal variations in the dilution rates showed that the highest dilution rate was obtained in winter while the lowest dilution rate was in summer. As the effluent discharges are increased with the treatment capacity expansion to be completed by 2011, the dilution rates are expected to be much reduced and the near-field stability of the wastefields will become unstable due to the increased effluent discharges.

• Journal of Radiation Protection and Research
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• v.23 no.1
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• pp.1-6
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• 1998

A diffusion model of radioactive liquid effluents is developed and applied for YGN NPP's site, based on the Gaussian plume type model. Due to the complexity of oceanic diffusion characteristics of YGN site, a simple and reliable statistical model based on Reg. Guide 1.113 is developed. Also, a computer code package to calculate dilution factors as a function of plant operation conditions and pathway of radioactive materials. A liquid effluents diffusion model is developed by dividing the diffusion range into two categories, i. e, a near field mixing region and a far field mixing region. In the near field, the initial mixing is affected by a buoyance force, a high initial turbulence and momentum which is characterized by a plant operation condition and environmental conditions. The far field mixing is similar to gaseous effluents diffusion. So, beyond the near field region, wellknown Gaussian plume model was adopted. A different area averages of Gaussian plume equation was taken for each radioactive exposure pathway. As a result, we can get different dilution factors for different pathways. Results shows that present dilution factors used for YGN ODCM is too much overestimated compared with dilution factors calculated with the developed model.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1999.10a
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• pp.243-252
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• 1999

Recently several research groups using CORMIX, approved by EPA, have been working on the hydrodynamic mixing processes due to the ocean discharges. It provides a useful tool for analyzing near field mixing characteristics through the outfall system. This paper applies CORMIX 1 & 2 to the Pusan Jungang Effluent Outfall System, which is planned to be in the Gamchun harbour and will be completed in 2011. This model output shows the trajectoral variation of dilution and concentration for three cases of outfall system. Dilution differences have been simulated and found the highest dilution condition under the different displacement of outfall system. On the basis of these outputs it will be proposed the optimum outfall system type and location. This approach might contribute on protecting the serious water quality problem due to the ocean discharge.

• Journal of Korean Port Research
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• v.14 no.2
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• pp.241-249
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• 2000

The amount of municipal water has been increased rapidly up to now and it is necessary to treat and dispose the wastewater effectively. The recent trend of the effluent disposal system, after treatment, show a nearshore discharge which has an outfall with length somewhere between the shoreline discharge and an extended deepwater outfall. There is no universal solution to municipal water treatment and disposal and each case must be examined on its merits and on economic, technical and environmental bases. In this study we focused mostly on the scientific and engineering aspects of ocean disposal through the outfall. For this purpose, we made an investigation to the near-field characteristics of discharged water and made some comparison with the existing experimental results. We also applied it to the Pusan Jungang Effluent Outfall System, which is planned to build in the Gamchun harbour and will be completed in 2011. The model output showed the trajectoral variation of dilution and mixing behavior for three cases of outfall system. Dilution differences have been simulated and found the highest dilution condition under the different displacement of outfall system. On the basis of these outputs it will be proposed the optimum outfall system type and location.

• Ocean and Polar Research
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• v.22 no.2
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• pp.69-80
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• 2000

A 3-D particle tracking model with normalized characteristic equations has been developed to predict the variation of near-field mixing characteristics and the far-field transport of the effluent plumes discharged from sea outfalls. The model was applied to the case study on the Masan sea outfall plumes discharged through a submerged multiport-diffuser. Numerical simulations of the effluent transport for 15 days which cover neap and spring tidal cycles in Masan Bay were conducted using fall velocities of the solid wastes and the initial plume characteristics obtained from normalized near-field characteristic equations. The results showed that time variations in near-field minimum dilutions with tidal ambient flow conditions are about $45{\sim}49$. Most of the heavy particles in the effluent plumes were settled and deposited in the vicinity of the outfalls immediately, and the finer particles were transported eastwards 3 km away from the outfalls for 15 days. A similar depositional trend of contaminated sediment was also found during a recent field survey.

• Journal of the Korean Society of Safety
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• v.27 no.5
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• pp.35-41
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• 2012

The Numerical simulation was performed on the flow field around the two-dimensional rectangular bluff body in order to complement the previous experimental results of the bluff body stabilized flames [1]. For both fuel ejection configurations against an oxidizer stream, the flame stability was affected mainly by vortex structure and mixing field near bluff body. FDS(Fire Dynamic Simulator) based on the LES(Large Eddy Simulation) was employed to clarify the isothermal mixing characteristic and wake flow pattern around bluff body. The air used atmosphere and the fuel used methane. The result of counter flow configuration shows that the flow field depends on air velocity but the mixing field is influenced on the fuel velocity. At low fuel velocity the fuel mole fraction is below the flammable limit and hence the mixing is insufficient to react. Therefore, as the result, the flame formed at low fuel velocity is characterized by non-premixed flames. For the flow field of co-flow configuration, flame stability was affected by fuel velocity as well as air velocity. the vortex generated by fuel stream has counter rotating direction against the air stream. Therefore, the momentum ratio between air and fuel stream was important to decide the flame blow out limit, which is result in the characteristic of the partially premixed reacting wake near extinction.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.455-458
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• 2002

Mixing zone characteristics of the wastewater effluents discharged from an ocean outfall have been investigated using an outfall mixing zone analysis method. This analysis was applied to Sokcho ocean outfall case and was used to simulate the concentration distribution of wastewater effluents. Hourly concentration distributions of outfall effluent discharges were averaged for the period of 15 days. The results show that near-field dilution was relatively high with the dilution of 130 for the winter season.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.3
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• pp.389-396
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• 2008

The hybrid model can be used to predict the initial near field mixing and the far field transport of the buoyant jets, which are discharged from the submerged wastewater ocean outfall. In the near field, the jet integral model can be used for single port diffusers while the ${\sigma}$ transformed particle tracking model was used in the far field. In this study, the experimental study was performed to verify the developed hybrid model in the previous research. The developed hybrid model properly predict the surface and vertical concentration distribution of the single buoyant jets with various effluent and ambient conditions. The hybrid model can also simulate the surface concentration distribution of the rosette diffuser except for the parallel diffuser with the higher densimetric Froude number due to the assumption that dynamic effects of the effluent plumes are negligible in the far field. The application of the hybrid model to rosette diffusers can predict the concentration near the diffuser more accurately when the line-plume approximation is used.

• Journal of the Korean Society of Combustion
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• v.17 no.4
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• pp.60-65
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• 2012

The MILD combustion and pollutant emission characteristics were investigated computationally. The temperature of supplying air-stream and mixing rate (${\Omega}$) of exhaust gas in the air-stream were adjusted to investigate the effects of those parameters on the MILD combustion in jet flow field. The emission indices for NO (EINO) and CO (EICO) were introduced to quantify the amount of those species emitted from the combustion. The high-temperature region disappeared gradually as the mixing rate increased for fixed air-stream temperature. The EINO increased as the air-stream temperature became higher for fixed mixing rate, and the EINO decreased dramatically with increasing the mixing rate for each air-stream temperature condition. The EICO also decreased with increasing the mixing rate and it was nearly independent of air-stream temperature except for near ${\Omega}$ = 0.7. It was found that the CO supplied in the air-stream can be destroyed in the MILD combustion over the certain mixing rate.

• Proceedings of the Korea Water Resources Association Conference
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• 1995.05a
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• pp.191-196
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• 1995