The Gas Penetration Through Viscoelastic Fluids With Shear-Thinning Viscosity in a Tube

Abstract

The gas penetration of a long bubble through a viscoelastic fluid in a tube was studied. Experiments were carried out for two Newtonian and five polymeric solutions to investigate the relation between the coating film thickness and rheological properties of the test fluids. The polymeric solutions are viscoelastic fluids having shear-thinning viscosity. A bubble of air was injected into a tube filled with a test fluid to form hydrodynamic coating on a tube wall. The film thickness was evaluated by hydrodynamic fractional coverage m. The fractional coverage was characterized using the capillary number Ca and the Weissenberg number Wi. For viscoelastic fluids, Ca and Wi were evaluated considering the shear-thinning viscosity. Two kinds of representative shear rate were used for the evaluation of Ca and Wi. The dependence of m on Ca in viscoelastic fluids was different from that of the Newtonian case. The film was thinner than that of the Newtonian case at the same Ca when Wi was small, i.e. the viscous property was dominant. The shear-thinning viscosity had a role to make the film thin. On the other hand, the film tended to be thicker than the corresponding Newtonian results at large Wi because of normal stress effect.

Deposition of shear‐thinning viscoelastic fluids by an elongated bubble in a circular channel regarding the weakly elastic regime

“…Here, $$Wi$$ represents the ratio of first normal stress differences to the viscous shear stresses and reflects the importance of elasticity in the flow. Yamamoto et al 25 . and Boehm et al 27 .…”

The Long Bubbles Penetration through Viscoelastic Fluids with Shear-Thinning Viscosity in a Curved Tube

“…Gas passing through the bend cavity will tend to the inside, resulting in nonuniform wall thickness inside and outside and empting the area eccentric phenomena after the gas is blown. Yamamoto et al [10] analyzed Newtonian and non-Newtonian fluids using experimental methods and investigate the effect of Ca and Wi to . Sousa et al [11] use the experimental model; the non-Newtonian fluid polyacrylamide (PAA) is injected into the vertical tube by the CCD camera captured images of bubbles, and then the shape of the bubble with a dimensionless manner is presented.…”

Penetrating flows with gelation due to addition of counter ions to surfactant solution in circular tube

“…Penetrating flows with gelation due to addition of counter ions to surfactant solution in circular tube Takehiro YAMAMOTO *1 , Naoki TAKAMIDO *2 and Hayato NISHIGUCHI *1 べ，弾性効果により壁面上に形成される液膜が厚くなることを示した．Yamamoto ら (Yamamoto, et al, 2004)は 高分子水溶液への空気注入を研究し，高分子流体の shear-thinning 粘性と法線応力差が壁面上の液膜の被覆率に影 響することを示した．そして， shear-thinning 粘性の影響はワイセンベルグ数が 1 より小さいときに現れ，ワイセ ンベルグ数が 1 より大きいときには法線応力差の影響が現れることを見いだした． 溶解性流体の貫入流れでは，界面張力による安定化の効果は弱くなる．円管内の貫入流れでは，Scoffoni ら (Scoffoni, et al, 2001)が垂直管内の貫入流れの実験を行い，界面不安定が発生する臨界速度と二流体の粘度比と の関係を調べた．さらに，二種類の不安定モード(コークスクリュー・モードと軸対称モード)が観察されるこ とを示した．Kuang ら (Kuang, et al, 2004)は，円管内の貫入流れについて，界面先端付近の流動パターンを PIV 計測により観測し，貫入する流体(コア部)の外側の流動パターンに対する Taylor (Taylor, 1961)の仮説とコア 内部の流動パターンに対する Petitjeans と Maxworthy (Petitjeans and Maxworthy, 1996)の仮説を実証した．近年， 二流体界面の安定化技術の開発を目的として，降伏応力を有する流体を潤滑流体に用いて，その中に粘塑性流体 を流す円管内貫入流れが研究されている (Huen, et al, 2007, Hormozi, et al, 2011 (Chen and Rothstein, 2004, Hashimoto, et al, 2006, Ouchi, et al, 2006, Yamamoto, et al, 2008やシアバンディング (Berret, 2006, Ezrahi, et al, 2006, Manneville, 2008, Yamamoto, et al, 2009 は溶液中の自由なSal -の濃度を表す．Shikataら (Shikata, et al, 1987(Shikata, et al, , 1988…”