The methods of investigation of convective flows in multicomponent liquid, as well as their effect on the free surface of liquid are described. The choice of the system of equations and boundary conditions adequately describing the process of convective flows influence on the phenomena occurring on the surface is substantiated. The model and the basic thermodynamic quantities describing the state of the medium are described; approximate models are used in which low-energy motions are not taken into account, which leads to simplification of the fundamental equations and boundary conditions mentioned dependences. A set of basic dimensionless parameters and similarity criteria characterizing convection in a liquid is given.