巻号一覧
26 巻 (1998)
- 4 号 p. 191-
- 3 号 p. 137-
- 2 号 p. 75-
- 1 号 p. 7-
26 巻, 1 号
選択された号の論文の8件中1～8を表示しています
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方 義, 長谷川 富市, 反町 和則, 鳴海 敬倫, 竹村 茂雄1998 年 26 巻 1 号 p. 7-14
発行日: 1998/03/15
公開日: 2012/11/20
ジャーナル フリーWavelet analysis of the wall pressure fluctuation in drag reducing pipe flow has been made for various dilute polymer solutions and aqueous detergent solutions in order to discuss the correlation between drag reduction and pressure fluctuation. In the diagram of the root mean square of pressure fluctuation vs Reynolds number under the transition conditions, the peak is observed at a higher Reynolds number for drag reducing fluids than for water, and the magnitude of pressure fluctuation is also larger for the former fluid in averge than the latter. Wavelet analysis shows that pressure fluctuation is characterized by the peaks with high amplitudes appearing intermittently in time and that those high peaks tend to concentrate on a specific frequency range in the flow of drag reducing fluids.抄録全体を表示PDF形式でダウンロード (1608K) -
薄井 洋基, 伊藤 貴康, 佐伯 隆1998 年 26 巻 1 号 p. 15-19
発行日: 1998/03/15
公開日: 2012/11/20
ジャーナル フリーThe measurements of the rheological properties of quaternary ammonium salt cationic surfactant solutions were carried out by means of a cone-plate rheometer and a capillary viscometer. Experimental results showed a non-linear shear stress-shear rate relationship over a wide range of shear rates. Combined with the damping factor model for viscoelastic fluids, the non-linear viscosity relationship was successfully used to predict the turbulent flow characteristics in a drag-reducing surfactant flow.抄録全体を表示PDF形式でダウンロード (937K) -
渡邉 博, 長谷川 富市, 鳴海 敬倫, 平井 康行, 田辺 勝利1998 年 26 巻 1 号 p. 21-26
発行日: 1998/03/15
公開日: 2012/11/20
ジャーナル フリーFlow of dilute polymer solution through a small orifice has been examined by experimental and numerical analyses. In the flow near the exit of orifice, the measured centerline velocity gives a good agreement between water and PEO-18 100ppm aqueous solution, and it almost coincides with the numerical result for Newtonian fluid. Next, the elongational stress of the polymer solution is estimated using the flow through a small orifice. In the earlier study, the flow was apploximated as a converging flow towards an apex of a corn in a flow region upstream of an on fice. But, the present numerical and experimental analyses clarify that the real elongational rate is one order of magnitude smaller than that assumed in the former study. Therefore the former elongational rate is replaced with the new elongational rate and the elongational stress is estimated. The result shows that the elongational stress has a good fit to the data obtained for orifices and nozzles. It is concluded that the present method using a small orifice is useful for estimating the elongational stress of dilute polymer solution.抄録全体を表示PDF形式でダウンロード (1129K) -
小柴 孝, 森 教安, 中村 喜代次1998 年 26 巻 1 号 p. 27-34
発行日: 1998/03/15
公開日: 2012/11/20
ジャーナル フリーThe viscoelastic flow through the rectangular duct containing cylinder array, which is one of the model channels of porous media, is examined experimentally. Test fluids used are 0.01wt%, 0.1wt%, and 1.0wt% aqueous solutions of polyacrylamide (PAA). In the measurement of pressure loss, the excess pressure loss occurs as reported for the flow in the porous media. It is found that the onset of the excess pressure loss is related to the stretch-thickening property in the elongational viscosity of the PAA solution and also depends on the polymer concentration and the channel geometry. Furthermore, the flow patterns in the cylinder arrays, which include the converging-diverging and winding flow, suggest that the occurrence of excess pressure loss is caused by the elongational property for the PAA solutions.抄録全体を表示PDF形式でダウンロード (6006K) -
森 教安, 中村 喜代次1998 年 26 巻 1 号 p. 35-39
発行日: 1998/03/15
公開日: 2012/11/20
ジャーナル フリーNumerical simulations of the steady shear flows of Gay-Berne (GB) fluids are carried out using the SLLOD algorithm. The full GB potential and the WCA-repulsive GB potential are used for examining the effect of attractive force acting between molecules. In equilibrium, the attractive force is found to be effective in the formation of ordered phases, that is the nematic phase and the smectic phase. In the steady shear flow, the calculations are performed at the various reduced densities and the shear rate dependences of the structure and the rheological properties are studied. The attractive force affects not only the rheological properties but also the orientational order parameter of the system at low shear rates.抄録全体を表示PDF形式でダウンロード (1059K) -
中 雄一, 千葉 訓司, 中村 喜代次1998 年 26 巻 1 号 p. 41-47
発行日: 1998/03/15
公開日: 2012/11/20
ジャーナル フリーFlow visualization experiments of shear-thinning aqueous polyacrylamide solutions through a tubular contraction were carried out using the tracer method for studies on the transition from the steady flow regime to the unstable flow regime and on the structure of the unstable flow.
It has been found that two basic transition patterns can be identified according to flow properties of polymer solutions and contraction ratio. The one is observed in rather dilute solution flows through a tube with a small contraction ratio. In this case, the secondary flow vortex decays with an increase in flow rate, then the unstable flow becomes observable when the secondary flow is almost completely diminished. In the unstable flow there are several stream bundles, which consist of two counterrotating vortex tubes, i. e. Goertler-like vortices, and three dimensional lip vortices between them. The other is observed in rather concentrated solution flows through a tube with a large contraction ratio. In this case, the secondary flow vortex grows with an increase in flow rate. The unstable flow is characterized by the fact that the secondary flow vortex grows and decays alternately. Furthermore, it has been confirmed that flow observations near the entrance face are useful and fundamental means for understanding of three dimensional flow structure as well as detailed structure of the secondary flow vortex.抄録全体を表示PDF形式でダウンロード (11410K) -
K. Osaki, H. Watanabe, T. Inoue1998 年 26 巻 1 号 p. 49-52
発行日: 1998/03/15
公開日: 2012/11/20
ジャーナル フリーFirst we show that the Cox-Merz rule, that η(γ) is approximated by η*(ω)|γ=ω, exhibits considerable deviations for systems with very strong or weak damping functions for the strain-dependent relaxation modulus; here η*(ω) is the complex viscosity. The deviation can be accounted for in view of the BKZ constitutive model. Secondly we propose an equation to approximate the first normal stress coefficient, ψ1(γ), from the dynamic modulus, G′(ω); ψ1(γ)≅2G′(ω)/ω2|γ=κ′ω. Here κ′ is an adjustable parameter. It is proved that this equation is almost equivalent to a Gleissle formula, ψ1(γ)≅ψ1+(t)|γ=κ/t with κ′=/1.55, where ψ1+(t) is the growth function of the first normal stress coefficient at the start-up of shear flow at the limit of zero rate of shear. The normal stress coefficient is approximated well over a wide range of rate of shear for the data by Laun of IUPAC A polyethylene and those for a solution of polystyrene with a narrow molecular mass distribution. The appropriate values of κ′ for these systems over moderate ranges of γ were 2.0 and 1.4, respectively. These values are related to the damping function through the BKZ model and may be estimated from the damping function, approximated as exp(-αt), with a relation κ′≅0.37/α.抄録全体を表示PDF形式でダウンロード (626K) -
Youn Cheol Kim, Hansol CHO, In Jae CHUNG1998 年 26 巻 1 号 p. 53-59
発行日: 1998/03/15
公開日: 2012/11/20
ジャーナル フリーThe effects of thermal history and rigid units on rheological properties of thermotropic liquid crystalline (TLC) polyesteramides with bulky side group were studied by differential scanning calorimetry (DSC) and static and dynamic viscoelastic measurements. Rheological properties of TLC polyesteramides were largely dependent on the amount of the rigid unit as well as the annealing condition. The effect of thermal history on dynamic moduli was investigated above and below the transition temperature of metastable equilibrium state defined by Cheng. G′(dynamic storage modulus) and G″(dynamic loss modulus) of TLC polyesteramides measured above the transition temperature (280°C) were little affected by the amount of the rigid unit and the thermal history, whereas below the transition temperature (220°C) both were largely dependent on the thermal history. These dependencies were also confirmed satisfactorily by the DSC measurement. The copolyesteramide (X=0.7) showed viscoelastic behavior with a longer relaxation time in the molten state than the homopolyesteramide (X=1.0), because the nematic mesophase became more prominent as the amount of rigid unit increased.抄録全体を表示PDF形式でダウンロード (3318K)
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