• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.12
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• pp.2376-2384
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• 1992

A theoretical analysis is carried out to predict the characteristics of transient ignition phenomena for the spherical fuel droplets cloud with non-uniform droplet size and number density distribution. Numerical calculations are performed for various cases depending on the combinations of the major parameters such as ambient temperature and initial distributions of droplet size and number density. The results of present study show that the ignition delay decreases for higher ambient temperature and smaller droplet size. Droplets cloud of hollow type with outer concentrated distribution ignites most rapidly.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.3 s.258
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• pp.283-291
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• 2007

The static pressure distribution, atomization characteristics and velocity distribution of tapered nozzle swirl spray is analyzed and then compared with original swirl spray. The static pressure distribution inside the swirl spray is measured using a piezoresistive pressure transducer. Phase Doppler anemometry (PDA) is applied to measure and analyze the droplet size and velocity distribution of tapered nozzle and original swirl spray. The static pressure inside the spray shows the lower value compared to the atmospheric pressure and this pressure drop is getting attenuated as the taper angle is increased. The droplet size of tapered nozzle spray shows similar value compared to the original swirl spray at the horizontal mainstream while it shows increased value at vertical mainstream. The deteriorated atomization characteristics of tapered nozzle spray is improved by applying high fuel temperature injection without causing the spray collapse. The velocity results show that the larger portion of fuel is positioned with higher injection velocity, and the smaller portion of fuel is positioned with lower injection velocity with causing spatially non-uniform mixture distribution.

• 한국전산유체공학회:학술대회논문집
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• 2008.03a
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• pp.186-196
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• 2008

The dependence of the rheological properties of blood on shape, aggregation, and deformability of red blood cells (RBCs) has been investigated using hybrid systems by coupling fluid with solid models. We present a simple approach for simulating blood as a multi-component fluid, in which RBCs are modeled as droplets of acquired biconcave shape. We used lattice Boltzmann method (LBM) due to its excellent numerical stability as a simulation tool. The model enables us to control the droplet static shape by imposing non-isotropic surface tension force on the interface between the two components. The use of the proposed non-isotropic surface tension method is justified by the Norris hypothesis. This hypothesis states that the shape of the RBC is due to a non-uniform interfacial surface tension force acting on the RBC periphery. This force is caused by the unbalanced distribution of the lipid molecules on the surface of the RBC. We also used the same concept to investigate the dynamic shape change of the RBC while flowing through the microvasculature, and to explore the physics of the Fahraeus, and the Fahraeus-Lindqvist effects.

• 한국전산유체공학회:학술대회논문집
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• 2008.10a
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• pp.186-196
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• 2008

The dependence of the rheological properties of blood on shape, aggregation, and deformability of red blood cells (RBCs) has been investigated using hybrid systems by coupling fluid with solid models. We present a simple approach for simulating blood as a multi-component fluid, in which RBCs are modeled as droplets of acquired biconcave shape. We used lattice Boltzmann method (LBM) due to its excellent numerical stability as a simulation tool. The model enables us to control the droplet static shape by imposing non-isotropic surface tension force on the interface between the two components. The use of the proposed non-isotropic surface tension method is justified by the Norris hypothesis. This hypothesis states that the shape of the RBC is due to a non-uniform interfacial surface tension force acting on the RBC periphery. This force is caused by the unbalanced distribution of the lipid molecules on the surface of the RBC. We also used the same concept to investigate the dynamic shape change of the RBC while flowing through the microvasculature, and to explore the physics of the Fahraeus, and the Fahraeus-Lindqvist effects.