| 초록 |
We performed the particle focusing under viscoelastic fluids in a straight square microchannel based on the so-called “elasto-inertial focusing”. Probability distribution functions (PDFs) were obtained at various flow rates (40 – 320 μl/h) and viscoelasticity of medium fluids (0.01 – 1.0 wt% PEO solutions). To evaluate focusing efficiency, the PDF values at the centerline of the channel were plotted as a function of two dimensionless numbers Reynolds number (Re) and Weissenberg number (Wi), respectively. As a result, the PDF as a function of Re does not display any tendency, but a master curve was obtained in the plot of PDF as a function of Wi. It might be due to relaxation time which is a typical characteristics of viscoelastic fluid, not like Newtonian fluid. It is also found that PDF value shows maximum value at Wi = 3.16. Less than Wi = 3.16, the particle focusing increase with increasing Wi. However particle not focus any more but scatter more with increasing Wi at larger than Wi = 3.16. Therefore, Wi is a more proper parameter to manipulate elasto-inertial focusing than Re. |
