Visualization
The main research strategy of our group is to see the motion of fluid, directly. Therefore, we utilize visualization techniques to understand fluid mechanics problems. Also, we work on developing flow visualization techniques as well.
Laser Interferometry
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We measure the vapor distribution of volatile liquid components by detecting a refractive index difference. This method is useful and reliable to understand the material transport in a wide range of research areas. We use this techniques to explore how often flower releases a floral scent (VOC, Volatile organic compounds) and how the droplet evaporates on/under the substrate.
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Related publication:
H. Kim, G. Lee, J. Song, and S.-G. Kim, "Real-time visualization of scent accumulation reveals the frequency of floral scent emissions," accepted in Frontiers in Plant Science.
Micro Particle Image Velocimetry ​
In our group, we try to visualize flow patterns using particle image velocimetry. For the small-scale fluid mechanics case, it is not easy to visualize the micro flow. However, we are expert on this.
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Tomographic Particle Image Velocimetry
To measure 3D-3C velocity vector components, four CCD cameras are used to observe one target. All cameras are installed under the microscope. There is a only one objective. This setup is very unique to measure micro flows.
Related publication:
Kim et al., "Full 3D-3Cvelocity measurement inside a liquid immersion droplet," Exp. Fluids 51(2), 395 (2011)
Kim et al., "Comparison of Tomo-PIV and 3D-PTV for microfluidic flows," Meas. Sci. Technol. 24(2), 024007 (2013)
Schlieren Method
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We use a Schlieren method to visualize a flow field without using tracer particles. On the left hand side, the example presents the turbulent flow due to the flame though a fire torch. This method can be used to investigate flow physics where the density or refractive index difference exists. We work on visualizing new physicochemical hydrodynamic features that have never been measured before.
Polarized Light Microscopy
This measurement method can be widely used to look a hidden structure, e.g. internal structure of materials and stresses on the complex liquids. For example, on the left, one image is for the regular bright-field image and the other is for the polarized light image. The objects are liquid crystals.