Studying the influence of turbulent mixing on thermonuclear burning regimes during X-ray bursts of neutron stars using the K ε model

We study the influence of turbulent mixing on the development of thermonuclear flashes in the surface layers of neutron stars. A simple K e model that includes various physical processes is used to describe the turbulent processes. In contrast to the widespread mixing-length theory, the K e model does not require using additional dimensional parameters, traces the development of turbulence in dynamics, describes the various turbulence development scenarios (gravitational and shear instabilities, convection, semiconvection, etc.) in a unified way, and can be used in multidimensional numerical simulations. Empirical constants of the model are chosen on the basis of experimental data and direct numerical simulations of typical processes. We have used the Era and Tigr-3T software packages to numerically simulate thermonuclear flashes in the accretion-renewable atmospheres of neutron stars. Turbulence is shown to accelerate significantly the transport of released energy to the stellar surface. Mixing equalizes the concentrations of matter components throughout the burning layer and increases the amount of matter involved in the thermonuclear burning during a flash.