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Volume 28 (2000)
- Issue 4 Pages 151-
- Issue 3 Pages 99-
- Issue 2 Pages 55-
- Issue 1 Pages 7-
Volume 28, Issue 1
Displaying 1-7 of 7 articles from this issue
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Tokunaga MasayoshiArticle type: Article
2000 Volume 28 Issue 1 Pages 7-12
Published: March 15, 2000
Released on J-STAGE: September 28, 2000
JOURNAL FREE ACCESSIn this work Reynolds' equation is extended to power law fluid or Ostwald-deWaele Fluid used as lubricant for a short journal bearing. The numerical data are obtained for various non-Newtonian fluids such as polymeric liquid comprising colloidal solution or healthy human blood, using the experimental data by G.W.Scott Blair. This thought may be important for fire prevention, simplification of pump system, and decrease of friction force like sigma-phenomenon and wall effect.View full abstractDownload PDF (460K) -
Adachi Hiromasa, Hasegawa Teruo, Kotani NobuyoshiArticle type: Article
2000 Volume 28 Issue 1 Pages 13-19
Published: March 15, 2000
Released on J-STAGE: September 28, 2000
JOURNAL FREE ACCESSIn this study, the dynamic modulus of some close-celled and open-celled polyethylene foams was determined by the dynamic viscoelastic measurements in tensile and compression modes. As a result, the dynamic compression modulus of some close-celled polyethylene foams is found to evaluate compression characteristics of foam as well as other dynamic properties, and those of some open-celled polyethylene foams is found not to evaluate. The dynamic compression modulus of some close-celled polyethylene foams have been clarified to correlate with the dynamic tensile modulus positively. In the Young's modulus of the close-celled polyethylene foams, the calculated value following from the two-dimensional model with six-angular pores analyzed by finite element method (FEM) using the plane stress element, was found to be in a reasonable agreement with the experimental data of the dynamic tensile modulus.View full abstractDownload PDF (599K) -
Mori Noriyasu, Yamamoto Ichiro, Nakamura KiyojiArticle type: Article
2000 Volume 28 Issue 1 Pages 21-26
Published: March 15, 2000
Released on J-STAGE: September 28, 2000
JOURNAL FREE ACCESSBrownian dynamics simulations of the shear flow for bimodal suspensions of oblong-particles were carried out. Two kinds of oblong particles were used: two-sites and four-sites model particles with the interparticle potential of a repulsive Lennard-Jones potential. At low shear rates, the flow-induced orientation of the system greatly depends on a mixture ratio of two-sites and four-sites particles. There is a transition to a hexagonal arrangement of string structure in the gradient-vorticity (y-z) plane at high shear rates, and the shear rate where the structural transition occurs becomes lower with increasing the number of four-sites particles. The formation of the string structure requires a large shear strain after an imposition of shear. Concerning the rheological properties of the systems, the number of four-sites particles affects the sear-thinning viscosity and normal stress effect. Furthermore, the formation of the string structure causes significant changes in the viscosity and the first normal stress difference.View full abstractDownload PDF (344K) -
Koshiba Takashi, Mori Noriyasu, Nakamura KiyojiArticle type: Article
2000 Volume 28 Issue 1 Pages 27-33
Published: March 15, 2000
Released on J-STAGE: September 28, 2000
JOURNAL FREE ACCESSViscoelastic flows through periodic undulating channels were numerically simulated with the HSMAC method by using the modified Giesekus model. The results obtained with a variety of the modified Giesekus fluids show the increment of flow resistance: the occurrence of excess pressure loss. The degree of the excess pressure loss depends on the stretch-thickening property of elongational viscosity as well as the amplitude and wavelength of undulating channel. The streamlines after the occurrence of the excess pressure loss indicate a significant swell in the expansion part because of the Barus effect. The distributions of stress power are presented in order to discuss the mechanism of the occurrence of the excess pressure loss, and the connection with stress relaxation property of the fluids is pointed out.View full abstractDownload PDF (599K) -
Saeki Takashi, De Guzman Manuel R., Morishima Hiroaki, Usui Hiromoto, ...Article type: Article
2000 Volume 28 Issue 1 Pages 35-40
Published: March 15, 2000
Released on J-STAGE: September 28, 2000
JOURNAL FREE ACCESSMeasurement of the velocity of a drag-reducing surfactant solution flow was carried out with the use of particle tracer velocimetry (PTV) to provide a better understanding of the mechanism of the drag reduction effect. From the results of the velocity data analysis, Reynolds stress is shown to be zero, but the turbulent intensity of the flow is still significant. The correlation between the two velocities at the pipe center and near the wall suggests that the flow of the drag-reducing surfactant solution is not a turbulent flow but some kind of a transitional flow. Such a transitional flow might include an intermittent laminar flow, which causes the Reynolds stress deficit.View full abstractDownload PDF (506K) -
Zong Zhengang, Yamane Hideki, Takahashi Masaoki, Hayashi Rika, Kimura ...Article type: Article
2000 Volume 28 Issue 1 Pages 41-46
Published: March 15, 2000
Released on J-STAGE: September 28, 2000
JOURNAL FREE ACCESSRheological properties of acylated chitosans with various acyl lengths were measured in the melt state. The acylated chitosans have two rheological transitions corresponding to rather abrupt decreases in viscoelastic functions and an abrupt drop in the height of plateau of the storage modulus. These transition temperatures become lower with increasing length of side chains. The time-temperature superposition principle was applied to dynamic viscoelastic functions for acylated chitosans. The time-temperature superposition fails for acylated chitosans with shorter acyl length. However, for an acylated chitosan with the longest acyl length, the viscoelastic data can be superposed into three separated master curves in different temperature ranges. Wide-angle X-ray diffraction measurements indicate that acylated chitosans have a layered structure. Temperature dependencies of d-spacing attributable to this layered structure indicate two transitions, whose temperatures reasonably correspond to those of the rheological transitions, exist. When the temperature exceeds the lower transition temperature, the d-spacing increases with increasing temperature, and the transition temperatures decrease with increasing length of side chains. The decreases of dynamic viscoelastic functions are associated with the layer spacing changes. It is suggested that the abrupt decrease of the plateau height is caused by the interchain movement of molecules or reorganization of the structure.View full abstractDownload PDF (276K) -
[in Japanese]Article type: Correspondence
2000 Volume 28 Issue 1 Pages 47
Published: March 15, 2000
Released on J-STAGE: September 28, 2000
JOURNAL FREE ACCESSDownload PDF (15K)
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