濃厚な粒子分散流体の急縮小流れにおける速度分布(流体工学,流体機械)  [in Japanese] Velocity Profiles of Concentrated Particle Suspensions in Abrupt Contraction Flows(Fluids Engineering)  [in Japanese]

Velocity profiles of concentrated fluid/particle mixtures in tube flows through an abrupt contraction were measured using magnetic resonance imaging (MRI). We used aqueous solutions of carboxymethyl cellulose (CMC) containing suspended particles at high volume fractions as test fluids. The particles used have spherical and slender shapes, respectively. These mixture fluids are opaque because of high concentration of particle. The channel used has a square cross section and an abrupt contraction geometry. As a result, a plug-like velocity profile was observed in the channel flow. Furthermore, we found that the velocity profile depends on the particle shape in the contraction. Spherical particle did not affect the flow field but slender particle caused a concave shape in the velocity profile near the centerline at upstream region of the contraction. This concave profile becomes obvious with increasing of volume fraction of particle. This result is caused by the elongational viscosity distribution of the slender particle suspension at the contraction.