  Flow structure stability of a steady radial thermocapillary flow from the
local heat source in cylindrical geometry has been studied numerically. The up
boundary of the liquid was partially covered by the stationary film of an
insoluble surfactant, pushed to the wall of the cavity. The calculations are
fulfilled on the base of interfacial hydrodynamics equations by using
mathematical package Comsol Multiphysics. It is shown that the effect of a
radial flow symmetry breakdown is appeared as a result of convective
instability, so that the initial poloidal rotation of the liquid transforms
into the azimuthal plane. The system of inclined steady volumetric vortices is
formed under the film of surfactant. The inclination angle of the plane of
rotation in dependence on the intensity of radial thermocapillary flow is
studied. It is shown that the azimuthal vorticity can be regulated by the power
of point-heat source and by free surface area. The increase of heating
intensity leads to the growth of the azimuthal vorticity. Thus, the initially
radially symmetric toroidal flow is divided into two parts with the origination
of vortices in the azimuthal plane under the film
