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**11** 

*Poland* 

Lech Gmachowski

*Warsaw University of Technology* 

**Hydrodynamic Properties of** 

versus their radius

**Aggregates with Complex Structure** 

Hydrodynamic properties of fractal aggregates and polymer coils, such as sedimentation velocity, permeability, translational and rotational diffusion coefficients and intrinsic viscosity, are of great interest in hydrodynamics, engineering, colloid and polymer science and biophysics. The hydrodynamic properties of aggregates are closely connected to their

Aggregates – the clusters of monomers - usually have a fractal structure which means that parts of the object are similar to the whole. The self-similar structure is characterized by the fractal dimension which is a measure of how the aggregate fills the space it occupies. The fractal dimension can be calculated by analyzing the mass-radius relation for a series of

The fractal dimension can be also determined by covering the aggregate with spheres of

in a log-log coordinate system, one determines the fractal dimension as the negative slope of

similar aggregates, since the mass of an aggregate scales as a power of the size.

changing radius (Fig. 1). Then plotting the number of spheres *N*

Fig. 1. Aggregate covering with spheres of changing radius.

**1. Introduction** 

the obtained line.

structure.

