Haward, Simon J.; Kitajima, Naoyuki; Toda-Peters, Kazumi; Takahashi, Tsutomu; Shen, Amy Q. published the artcile< Flow of wormlike micellar solutions around microfluidic cylinders with high aspect ratio and low blockage ratio>, SDS of cas: 123-03-5, the main research area is wormlike micellar solution flow microfluidic cylinder.
We employ time-resolved flow velocimetry and birefringence imaging methods to study the flow of a well-characterized shear-banding wormlike micellar solution around a novel glass-fabricated microfluidic circular cylinder. In contrast with typical microfluidic cylinders, our geometry is characterized by a high aspect ratio α = H/W = 5 and a low blockage ratio β = 2r/W = 0.1, where H and W are the channel height and width, and the cylinder radius r = 20μm. The small cylinder radius allows access up to very high Weissenberg numbers 1.9 ≤ Wi = λMU/r ≤ 3750 while inertial effects remain entirely negligible (Reynolds number, Re < 10-4). At low Wi values, the flow remains steady and sym. and a birefringent region (indicating micellar alignment and tensile stress) develops downstream of the cylinder. Above a critical value Wic ≈ 60 the flow transitions to a steady asym. state, characterized as a supercritical pitchfork bifurcation, in which the fluid takes a preferential path around one side of the cylinder. At a second critical value Wic2 ≈ 130, the flow becomes time-dependent, with a characteristic frequency f0 ≈ 1/λM. This initial transition to time dependence has characteristics of a subcritical Hopf bifurcation. Power spectra of the measured fluctuations become complex as Wi is increased further, showing a gradual slowing down of the dynamics and emergence of harmonics. Soft Matter published new progress about Algorithm. 123-03-5 belongs to class pyridine-derivatives, and the molecular formula is C21H38ClN, SDS of cas: 123-03-5.