• Journal of the Korea Society of Computer and Information
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• v.22 no.9
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• pp.149-154
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• 2017

The infusion of fluid and blood is necessary in the ward, operating room, recovery room, neonatal room, etc. for nutrition and blood supply to the patient, but air bubbles generated during infusion of fluid and blood circulate along the artery or vein. Serious illnesses occur and there is also a risk of death. In this paper, we propose a medical bubble detection system, a bubble detection system, a bubble detection alarm system, and a communication method in order to develop a safer fluid and blood injection system in the existing system, which is detected by a medical staff monitoring system or an ultrasonic bubble detection sensor In this study, infrared rays are transmitted to a tube through a tube for injecting fluid or blood into a patient, infrared rays transmitted by an infrared ray emitting section are received, and the amount of light is measured in real time. Based on the data, we study how to detect and analyze the presence of bubbles in fluid and blood.

• The Journal of the Acoustical Society of Korea
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• v.39 no.4
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• pp.227-236
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• 2020

This paper derives the insertion loss for the bubble layer of an air bubble curtain and an air masker which are used to reduce ocean anthropogenic noise such as the piling noise and the ship noise. The air bubble curtain is considered as a 'fluid-air bubble layer-fluid' model and the environment for the air masker is simplified as an 'vacuum-thin plate-fluid-air bubble layer-fluid' model. The air bubble layer in each model is assumed as the effective medium which has the complex wavenumber and the complex impedance corresponding to the bubble population distribution. The numerical simulations are performed to examine the insertion loss depending on the bubble population, the void fraction, and the thickness of the layer.

• Nuclear Engineering and Technology
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• v.44 no.6
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• pp.623-638
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• 2012

The volume of fluid (VOF) model of FLUENT and the lattice Boltzmann method (LBM) are used to simulate two-phase flows. Both methods are validated for static and dynamic bubble test cases and then compared to experimental results. The VOF method does not reduce the spurious currents of the static droplet test and does not satisfy the Laplace law for small droplets at the acceptable level, as compared with the LBM. For single bubble flows, simulations are executed for various Eotvos numbers, Morton numbers and Reynolds numbers, and the results of both methods agree well with the experiments in the case of low Eotvos numbers. For high Eotvos numbers, the VOF results deviated from the experiments. For multiple bubbles, the bubble flow characteristics are related by the wake of the leading bubble. The coaxial and oblique coalescence of the bubbles are simulated successfully and the subsequent results are presented. In conclusion, the LBM performs better than the VOF method.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.81-86
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• 2001

Interfacial pressure jump terms based on the physics of phasic interface and bubble dynamics are introduced into the momentum equations of the two-fluid model for bubbly flow. The pressure discontinuity across the phasic interface due to the surface tension force is expressed as the function of fluid bulk moduli and bubble radius. The consequence is that we obtain from the system of equations the real eigenvalues representing the void-fraction propagation speed and the pressure wave speed in terms of the bubble diameter. Inversely, we obtain an analytic closure relation for the radius of bubbles in the bubbly flow by using the kinematic wave speed given empirically in the literature. It is remarkable to see that the present mechanistic model using this practical bubble radius can indeed represent both the mathematical well-posedness and the physical wave speeds in the bubbly flow.

• 한국전산유체공학회:학술대회논문집
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• 1999.05a
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• pp.48-57
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• 1999

This paper deals with the numerical simulation of the behavior of single bubble rising near the free surface. Volume fraction of fluid (VOF) method with continuum surface force (CSF) model, the well known method for two phase flow simulation is adopted. A bubble of spherical shape positioned beneath the free surface is assumed at the initial stage. The difference according to the fluid properties of surrounding medium is examined. Simulation results are depicted and explained with the time history of bubble shape, velocity field and vorticity distribution.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2700-2703
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• 2008

An experiment on bubble-driven flow was performed in order to understand fundamental knowledge of flow structure around a rising bubble in a stagnant fluid. The measurement technique consists of a combination of the three most often used PIV techniques in multiphase flows: PIV with fluorescent tracer particles, the digital phase separation with a masking technique and a shadowgraphy. The key point of the measurement is that the background intensity of a PIV recording can be shifted to a higher level than a bubble region using a shadowgraphy in order to distinguish from fluorescent particles and a bubble as well. Flow fields were measured without an inaccurate analysis around a fluid-bubble interface by using only one camera simply.

• The KSFM Journal of Fluid Machinery
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• v.5 no.1 s.14
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• pp.7-12
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• 2002

As the first step to investigate the fundamental mechanism of a dispersed two-phase flow, we studied the detailed interactions between bubble or particle motion and flow around it. Experiments were carried out with a rising bubble or particle in stagnant water in a vertical pipe. Particles with different densities, and/or different shapes were used for comparison with a bubble. We adopted 3D-PTV (Three-Dimensional Particle Tracking Velocimetry) for measuring the bubble or particle motions, and PIV (Particle Image Velocimetry) for measuring the water flow simultaneously (Hybrid PIV). The experimental results showed that the oblate spheroidal solid particle rose along the longer axis direction at the point that the inclination of the longer axis reached the maximum, and the inclination direction changed after moving. The bubble moved to the direction that the spheroid's projected width grew up to the largest, and the minor axis of the oblate spheroidal body of the bubble was parallel to the moving direction. The trajectory of the center of the particle/bubble which was measured with 3D-PTV, was marked on the section (x-y) of the pipe. It exhibited the pattern of the particle/bubble motion.

• The KSFM Journal of Fluid Machinery
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• v.14 no.3
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• pp.10-17
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• 2011

Free energy based lattice Boltzmann method (LBM) has been used to simulate the contact angle and the bubble necking with large density ratio. LBM with the proper contact angle model is able to reduce the spurious currents and eliminate the singularity in the contact lines. The numerical results of the contact angles are satisfied with the Youngs law. For bubble necking flows, simulations are executed for various viscosities and contact angles. The phenomena of the bubble necking are simulated successfully and the subsequent results are presented. The present method is also applicable to the nucleate boiling flows.

• Nuclear Engineering and Technology
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• v.53 no.4
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• pp.1119-1126
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• 2021

Spacer grid with mixing vane had been widely used in nuclear reactor core. One of the main feather of spacer grid with mixing vane was that strong swirl flow was formed after the spacer grid. The swirl flow not only changed the bubble generation in the near wall field, but also affected the bubble behaviors in the center region of the subchannel. The interaction between bubble and the swirl flow was one of the basic phenomena for the two phase flow modeling in fuel assembly. To obatin better understanding on the bubble behaviors in swirl flow, full three dimension numerical simulations were conducted in the present paper. The swirl flow was assumed in the cylindral calculation domain. The bubble interface was captured by Volume Of Fluid (VOF) method. The properties of saturated water and steam at different pressure were applied in the simulation. The bubble trajectory, motion, shape and force were obtained based on the bubble parameters captured by VOF. The simulation cases in the present study included single bubble with different size, at different angular velocity conditions and at different pressure conditions. The results indicated that bubble migrated to the center in swirl flow with spiral motion type. The lateral migration was mainly related to shear stress magnitude and bubble size. The bubble moved toward the center with high velocity when the swirl magnitude was high. The largest bubble had the highest lateral migration velocity in the present study range. The effect of pressure was small when bubble size was the same. The prelimenery simulation result would be beneficial for better understanding complex two phase flow phenomena in fuel assembly with spacer grid.

• The KSFM Journal of Fluid Machinery
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• v.13 no.4
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• pp.31-36
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• 2010

Free energy based lattice Boltzmann method (LBM) has been used to simulate the rising bubble flows with large density ratio. LBM with compact discretization is able to reduce the spurious current of the static bubble test and be satisfied with the Laplace law. The terminal rise velocity and shape of the bubbles are dependent on Eotvos number, Morton number and Reynolds number. For single bubble flows, simulations are executed for various Eotvos number, Morton number and Reynolds number, and the results are agreed well with the experiments. For multiple bubbles, the bubble flow characteristics are related by the vortex pattern of the leading bubble. The coalescence of the bubbles are simulated successfully and the subsequent results are presented. The present method is validated for static, dynamic bubble test cases and compared to the numerical, experimental results.