Microfluidics
We use microfluidics devices to investigate our interesting problems including 1) interfacial phenomena, 2) colloidal science, 3) bio- and nature-inspired fluid mechanics problems, and 4) physicochemical hydrodynamics problems.
n = 0.7
n = 0.8
The characteristics of vortical structures in T-shaped branches with respect to the shear-thinning effect are numerically investigated using a power-law fluid model. By varying the power-law index n, we observe three different flow structures, namely, steady-, harmonic-, and turbulent-like regimes. As the shear-thinning behavior became important, we observed the turbulent-like regime.
Related publication:
J. Kim, J. Ahn, and H. Kim, "Characterization of vortical structures in T-shaped branch depending on shear-thinning," Phys. Fluids. 33(3), 033107 (2021)
Emulsion stability is crucial in industries like food, pharmaceuticals, cosmetics, and paints. It ensures products maintain their desired state, preventing issues like creaming in foods or uneven color in paints. In pharmaceuticals and cosmetics, stability is paramount for consistent dosages and product performance. This scientific understanding allows for the optimization of formulations, leading to more reliable and innovative end products. Embracing emulsion stability is key to meeting consumer expectations, complying with regulations, and advancing product quality across diverse industries. We investigate the stability of emulsions using capillary microfluidics device.
In microfluidics applications, it is crucial to enhance the mixing efficiency with less input energy. In our work, we introduced a novel method to mix the sample using vapor-driven solutal Marangoni flows. The method only needs a highly volatile liquid components (e.g., ethanol or acetone, etc) placing next to the sessile drop sample.
Related publication:
J. Park, J. Ryu, H.J. Sung, and H. Kim, "Control of solutal Marangoni-driven vortical flows and enhancement of mixing efficiency," J Colloid Interf. Sci., 561, 408-415 (2020)
In the soft microchannels, the droplet polydispersity is decreased for a wide range of oil phase flow rates. As the membrane thickness decreases, the bending stiffness decreasesand we observe that the polydispersity decreases accordingly.
Related publication:
Y. Pang, H. Kim, Z. Liu, and H. A. Stone, "A soft microchannel decreases polydispersity of droplet generation," Lab Chips 14, 4029 (2014)