Pii: S0377-0273(00)00239-0
نویسندگان
چکیده
The shear viscosity of a suspension of deformable bubbles dispersed within a Newtonian ̄uid is calculated as a function of the shear rate and strain. The relative importance of bubble deformation in the suspension is characterized by the capillary number (Ca), which represents the ratio of viscous and surface tension stresses. For small Ca, bubbles remain nearly spherical, and for suf®ciently large strains the viscosity of suspension is greater than that of the suspending ̄uid, i.e. the relative viscosity is greater than 1. If Ca . O(1) the relative viscosity is less than one. In the limit that Ca! 1 (surface tension is dynamically negligible), numerical calculations for a suspension of spherical bubbles agree well with the experimental measurements of Lejeune et al. (1999, Rheology of bubble-bearing magmas. Earth Planet. Sci. Lett., vol. 166, pp. 71±84). In general, bubbles have a modest effect on the relative viscosity, with viscosity changing by less than a factor of about 3 for volume fractions up to 50%. q 2001 Elsevier Science B.V. All rights reserved.
منابع مشابه
Colour constancy from temporal cues: better matches with less variability under fast illuminant changes
To test whether temporal transient cues could improve colour-constancy estimates, surface-colour matches were made across two Mondrian patterns illuminated by different daylights: the patterns were presented either in the same position in an alternating sequence or, as a control, simultaneously side-by-side. The degree of colour constancy was significantly higher with sequential stimulus presen...
متن کاملFitting rectilinear polygonal curves to a set of points in the plane
In this paper two problems of ®tting rectilinear polygonal curves to a set of points in the plane according to the minimax approximation are considered. The constraints are, respectively, on the number of vertices and length of the polygonal curve. In both cases ecient algorithms are developed.
متن کاملPii: S0377-0273(00)00199-2
The Pedregal lavas are fresh, well-exposed basaltic ̄ows erupted from the Xitle scoria-and-cinder cone in the southwestern part of the Basin of Mexico. These lavas cover an area of 70 km and were emplaced over pyramids and other buildings (e.g. Cuicuilco and Copilco archaeological sites). Today, a part of Mexico-City (including the National University) is built on the ̄ows. Initial strombolian a...
متن کاملPii: S0377-0273(00)00148-7
The common occurrence of tree and pole blow-down from pyroclastic currents provides an opportunity to estimate properties of the currents. Blow-down may occur by uprooting (root zone rupture), or flexure or shear at some point on the object. If trees are delimbed before blow-down, each tree or pole can be simulated by a cylinder perpendicular to the current. The force acting on a cylinder is a ...
متن کاملPii: S0377-0273(00)00238-9
Data from a dual-frequency GPS network operated continuously from May 1998±October 1999 on Taal volcano, Philippines, were processed on a daily basis to monitor processes of crustal deformation associated with volcanic activity. During the 16-month period of observations, displacements totaled nearly 30 mm in the horizontal and 50 mm in the vertical over 2.7 and 5.8 km baselines. Relative site ...
متن کامل