落球法による気泡を含む液体の実効粘度の計測(流体工学,流体機械)

概要

論文の詳細を見る
The effective viscosity of bubbly liquid is measured by means of falling sphere method in Stokes drag region. The method can evaluate the influence of bubble's transient deformation around the falling sphere. The relative viscosity, which is defined by the effective viscosity divided by the singlephase viscosity, is directly obtained by the ratio of the terminal falling velocity of the sphere. The results have shown the following points. 1) The relative viscosity at low capillary number agrees to the theoretical formula for the spherical bubble dispersion. 2) The relative viscosity drops down to less than unity as the capillary number gets higher than a critical value. 3) The critical capillary number is around 3.5 for the falling sphere method, and is much larger than that for simple shear flow. 4) The effective viscosity increasing mechanism by bubble's transient deformation is discussed with visualization results and some theoretical works done in the past.
社団法人日本機械学会の論文
2004-09-25