Kunji Chiba

Motion of a slender body in quiescent polymer solutions

The motion of a slender body falling in quiescent polymer solutions is investigated experimentally. It represents the simplest model of motion of single fibers in the flow of fiber suspensions. The fall behavior in quiescent polymer solutions is compared with that in water. It is demonstrated that a slender body falling in Newtonian liquids rotates to adopt a horizontal orientation, whereas in non-Newtonian liquids it rotates towards a vertical orientation but for less concentrated solutions is not able to reach the vertical orientation and moves sideways with a constant orientation angle. The effects of shear thinning and elasticity on the motion of the body are discussed.

Anomalous flow patterns in viscoelastic entry flow through a planar contraction

Abstract This paper adds further experimental evidence to demonstrate that the flow characteristics in planar contraction flows of shear-thinning aqueous polyacrylamide solutions are far more complex than initially supposed, with anomalous flow phenomena appearing in the unstable flow regime. It is confirmed that a lip vortex occurs at the re-entrant corner and it appears at lower flow rates with an increase in contraction ratio.

The structure of anomalous entry flow patterns through a planar contraction

Abstract The structure and origin of the so-called bundle-like streams which are generated near the salient corners in unstable planar entry flows of rather dilute polyacrylamide solutions have been studied. The flow visualization experiments using the dye-solution injection technique clearly show that a bundle consists of two counterrotating vortex tubes, i.e. Goertler vortices whose cross-section is almost rectangular.

Numerical solution for the flow of viscoelastic fluids around an inclined circular cylinder.

On obtient des solutions de differences finies par la methode des perturbations pour etudier linfluence dune augmentation de fluidite et de lelasticite sur lecoulement autour dun cylindre circulaire incline de longueur finie dans un ecoulement uniforme

Further Observations of Anomalous Entry Flow Patterns Through A Planar Contraction

The present paper adds further experimental evidence to show that the planar contraction flows of shear-thinning polyacrylamide aqueous solutions are far more complex than initially imagined, especially the presence of non-trivial 3-dimensional component has been confirmed for unstable flow regime, such as several bundles of stream near the side walls.