  Compared to the well-studied topic of human mobility in real geographic
space, very few studies focus on human mobility in virtual space, such as
interests, knowledge, ideas, and so forth. However, it relates to the issues of
management of public opinions, knowledge diffusion, and innovation. In this
paper, we assume that the interests of a group of online users can span a
Euclidean space which is called interest space, and the transfers of user
interests can be modeled as the Levy Flight on the interest space. To consider
the interaction between users, we assume that the random walkers are not
independent but interact each other indirectly via the digital resources in the
interest space. The model can successfully reproduce a set of scaling laws for
describing the growth of the attention flow networks of real online
communities, and the ranges of the exponents of the scaling are similar with
the empirical data. Further, we can infer parameters for describing the
individual behaviors of the users according to the scaling laws of the
empirical attention flow network. Our model can not only provide theoretical
understanding on human online behaviors, but also has wide potential
applications, such as dissemination and management of public opinions, online
recommendation, etc.
