Abstract: Theoretical prediction of macroscopic flow properties of complex liquids is challenging even in the simplest case of suspension of spherical particles. There are a few available theories to calculate viscosity of a complex liquid based on its microscopic structure. I will discuss those theories and show why the problem of homogenization is still developing and another approach is on demand. At the end of my talk I will discuss a prospective direction in the field which have recently emerged. In this approach homogenization is performed by numerical simulations of only a few particles which are immersed in the complex liquid described by its effective viscosity. Importantly, the effective viscosity is a function of the wave vector.