دانلود رایگان مقاله قابلیت بازسازی کل غیر فراکتال در جریان برشی ساده

abstract

A unique pattern interpreting the restructuring of non-fractal aggregate is established. The restructuring of an aggregate from initial structure toward a stable structure is well presented by a linear relation between the saturation degree of particle connection, and the inversed strength of aggregate. The dynamics of restructuring for different initial configuration of aggregate, from very loose to dense, in various simple shear flow condition is numerically performed. The temporal change in properties of aggregate is analyzed in terms of coordination number and volume fraction. The simulation employs Stokesian dynamics for the estimation of many-particle hydrodynamic interaction while the particle–particle interaction is calculated by van der Waals potential. Simulation results show that the aggregate restructures and exists in a stable state corresponding to the shear flow condition. The transition among the stable aggregates somewhat expresses reversible behavior. Especially in weak flow, the aggregate gradually reaches its limit structure whose properties such as coordination number and volume fraction are typically determined. Such limit aggregate plays an important role for predicting the restructuring of any non-fractal aggregate in any fluid condition. Moreover, the penetration effect of fluid flow on aggregate is discussed by means of porous sphere model.
2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved

4. Conclusion

The restructuring behavior of non-fractal aggregate in simple shear flow has been numerically investigated. The many-particle hydrodynamic interaction is estimated by Stokesian dynamics while the interparticle interaction is calculate from van der Waals potential. During the restructuring, the connectivity of the particles of the aggregate has changed toward a stable structure depending on the shear condition. The dependence of coordination number and volume fraction of aggregate on flow condition and nondimensional time is very complex. A linear relation of the saturation degree of particle connection, and the inversed strength of aggregate during restructuring is recognized. We have found the limit of restructuring: under weak flow, the aggregate obtains its most compact structure whose properties can be typically determined. Such limit aggregates play important role for the prediction of restructuring behavior.