Je-Eun Choi

Sub-micro particle distribution of measurement and simulation in cross-section of microchannel by process computed tomography

The application of process computed tomography to microchannels is considered in this paper. Using the process computed tomography system in microchannel, a particle distribution image can be obtained in a multiphase flow. Based on the reconstructed image, it is easy to estimate the particle diffusion behaviors in a fluid flow. A microchannel system is designed for process computed tomography. The particle and water were injected into the microchannel, and then the capacitance of the fluid flow was measured at the cross-section. The particle distribution of cross-section is estimated in the microchannel. Especially, it has been reconstructed that the 3-D image of particle distribution. Also, cross-sectional images of the particle distribution of a two phase flow are compared to results obtained from computer simulations.

A Hybrid PTV Using an Affine Transformation

PTV (Particle Tracking Velocimetry) has been limitedly used for the measurements of flow fields because there have been interpolation data loss which is inevitable to PTV in principle. In this paper, a hybrid PTV algorithm which eliminates interpolation data losses has been constructed by using an affine transformation. In order to evaluate the performances of the constructed hybrid PIV algorithm, an artificial image test was made using the Green-Taylor vortex data. The constructed algorithm was tested on the experimental images of the wake flow (Re = 5,300) of a rectangular body (6cm × 3cm), through which its excellence was demonstrated.Copyright

3D Tomographic Transition of Particle Distribution in Microchannel

The three dimensional cross-sectional particle concentrations of particle-liquid two phase flows in the two cross-seciton of microchannel has been reconstructed using process tomography. In the obtained 3D (2D space and time) reconstruction image, the dielectric particle-injected area appears to have a high particle concentration, and the deionized water-injected area appears to have a low particle concentration. Dielectric particles as the solid phase and non-conductive deionized water as the liquid phase are non-uniformly injected to the microchannel. The comparison between the qualitative result of 3D reconstruction image and the quantitative result of particle concentration in flow direction transition is that the particle is reasonably distributed in the particle injected area of the cross-section. Based on the reconstructed particle distribution image, it is easy to estimate the particle diffusion behaviors in microchannel.Copyright

2D Measurement and Simulation of Microparticle Cross-Sectional Distribution by Micro Process Tomography

The application of micro process tomography to microchannels is considered in this paper. Using the micro process tomography system in microchannel, a particle distribution image can be obtained in a two phase flow. Based on the reconstructed image, it is easy to estimate the particle movement in a fluid flow. A novel microchannel system is designed for electrical process tomography that includes 60 electrodes distributed cross-sectional at five positions. The particle and water were injected into the microchannel, and then the capacitance of the fluid flow was measured at cross-section of microchannel. The result showed the 2D image of particle distribution of cross-section in the microchannel. Also, cross-sectional images of the particle distribution of a two phase flow are simulated.Copyright

Impedance Measurement in Multilayer Connecter System of Micro Channel With Different Frequency

In investigating a microchannel, understanding regarding dispersion reaction are need to be acquire first down to the view point of multiphase flow dynamics. Usually, various measurements methods and in-depth analyzation are necessary to understand thoroughly the inside reaction occurs in this kind of system. In this experiment, fabricated multilayer microchannel with commercial connecter system was made for a tomography system with electrodes attached. This fabricated multilayer microchannel measures impedance using 12 electrodes from 5 different positions continuously. In measuring the impedance, it is necessary to consider the electric field caused by the electrodes and the force distribution inside the particles. Because of a non-uniform electric field distribution inside the system, forces inside the particles are not equal thus net force is present. This study, discuss how the frequency of the electric fields affects the particle position as a driving force to the microchannel system.Copyright

Flow Field Separating Technique in Bubbly Flow using Discrete Wavelet

Nowadays wavelet transforms are widely used for the analyses of PIV velocity vector fields. This is bemuse the wavelet provides not only spatial information of the velocity vectors but also of time and frequency domains. In this study, a discrete wavelet trC1f1

Application of Cross-Sectional Impedance Measurement Technique to Micro Channel

form has been applied to real PIV images of bubbly flows. The vector fields obtained by a self-made cross-correlation PIV algorithm were used for the discrete wavelet transform The performances of the discrete wavelet transform is investigated by changing the level of power of discretization. The decomposed images by the wavelet multiresolution showed conspicuous characteristics of the bubbly flows according to the level changes. The high spatial bubble concentrated area could be evaluated by the constructed discrete wavelet transform algorithm, at which high leveled wavelets could play a dominant roles to reveal the flow characteristics.

Fabrication of microchannel with 60 electrodes and resistance measurement

Fluid flow in microchannels has emerged as an important area of research due to its various applications in medical and biomedical industries, computer chips, and chemical separations. To fabricate microchannel devices, a thorough understanding of the diffusion reactions on the inside of the microchannel from the viewpoint of multiphase flow dynamics is needed. Electrical impedance tomography (EIT) is a recently developed imaging technique in which conductivity or permittivity images of a subject can be rapidly collected with channels of external electrodes. Usually EIT is visualized into a cross-sectional image representing the distribution of density. Therefore, the application of EIT to microchannels is considered in this paper. This research is a first step to developing EIT for microchannel nanoparticles concentrations in a microchannel with 60 electrodes and measured using the cross-sectional impedance measurement technique. Using the EIT system in a microchannel, a particle distribution image can be obtained in a magnetic fluid. Based on the reconstructed image, it is easy to estimate the particle diffusion behaviors in a fluid flow.Copyright