Formalism «Magneto Cross-Sections» of D– (A+ )-Centers at Resonance Scattering of Charged Carriers in Angenerated Semiconductors

The new approach to study of kinetic effects in covalent semiconductors is developed. On example of the calculation kinetic coefficients at resonance scattering some particularities of the proposed approach are demonstrated. Influence of limited weak magnetic field on kinetic effects is studied. Unlike standard method, taking into account presence of the H-field in the nonequilibrium distribution function with the following reception sought formulas for kinetic coefficients, in proposed approach presence (the influence) of the weak H-field is fixed as local (virtual) incrementation of crosssection of the concrete scattering, in this given case it’s resonance. Formal change   res eff 0 H    allows relatively easy to analyze the influence of the H-field on kinetic effects. It is shown that at presence of the H-field electronic conductivity reached the maximum near 1 K in the range of fields of the order 100 Gauss. General result is revealed in process of the calculation at any mechanism of the scattering. The main requirement is that the low-temperature asymptotics T 0 l  of concrete mechanism of the scattering should be constant

An Alternative Scheme to Calculate the Strain Rate Tensor for the LES Applications in the LBM

Large eddy simulations (LES) based on the Smagorinsky model can be conveniently used in the lattice Boltzmann method (LBM) because the strain rate tensor,Sij, used to determine the eddy kinematic viscosity can be calculated from the second-order moment of the nonequilibrium distribution function, and the current total nondimensional relaxation time can be determined explicitly. A new method is developed where the distribution function after the relaxation subroutine differs from that after the motion subroutine leading to a similar method to determineSij, but its application is inconvenient due to the implicit feature. However, the derivation also leads to an alternative explicit scheme for calculatingSijbased on physical analysis of the momentum transport process, where the stress tensor,Tij, is calculated first, and thenSijis determined fromTijusing the constitutive relationship for Newtonian fluid. The current total nondimensional relaxation time is also given explicitly so that this LES model can be easily used in the LBM.