Vol 61, No 8 (2016)

The model of an orthotropic nonlinear elastic compressible material generalizing the known model of an isotropic semilinear (harmonic) material and admitting a number of exact solutions at large strains is proposed. For this model of the material, an exact solution of the plane problem on large bending strains of a compound rectangular beam consisting of two layers, one of which is preliminarily deformed, is obtained. When formulating and solving the problem, the theory of superimposed large strains is used. On the basis of the calculations carried out, the effect of anisotropy on a strong bending of the compound beam with a preliminarily deformed layer is analyzed.

A general solution of the Boltzmann equation is presented. On its basis, a hypothesis about the internal structure of turbulence is proposed. An expression for the turbulent-friction coefficient is obtained. The criterion on the basis of which the solution of the Boltzmann equation can be attributed to the turbulent mode of flow is formulated.

In this study a two-dimensional model for calculating cavitation-bubble compression in benzene using a wide range of equations of state for ultrahigh pressures and temperatures is constructed. The calculations are carried out on the supercomputer of the Keldysh IAM. With the help of this model, the possibility of hits in the diamond-formation mode depending on the parameters of the external pressure and the initial bubble radius are analyzed. The dependence of the duration of the presence in the diamond-formation mode on these parameters is investigated.

The results of experimental and numerical investigations of the efficiency of control by an incompressible turbulent boundary layer with the help air blowing through a permeable wall fabricated with maintenance of most of the necessary requirements for the quality and configuration of microapertures and having a low effective roughness are analyzed. Various cases of modeling the process of air blowing into the boundary layer through a specified hi-tech finely perforated surface are considered, and the data for average parameters and characteristics of turbulence of the flow types under investigation are presented. A substantial decrease in the skin-friction coefficient along the model length, which can achieve 90% with increasing the blowing coefficient, is shown. The estimate of the energy consumption for the process of blowing under terrestrial conditions testifies to the high potential of this method of control capable to provide 4–5% gain in the total aerodynamic drag of a simple modeling configuration.

The methodology of efficient macroscopic calculation of parameters of the cubic crystal lattice based on the use of the coefficient of structured packing of its elementary cell is considered. The possibility of precision theoretical determination of the numerical values of interatomic distances in crystals of the type under consideration is shown.

Two-electron states with a zero pulse for the symmetry group of superconducting materials based on iron pnictides are considered. Cases are established for the introduction of one or two additional quantum numbers, notably, the internal quantum number, which characterizes single-electron states, or an additional quantum number, i.e. the irreducible representation index of the intermediate group. The octet structure of zeros observed in photoelectron spectra and the phase difference between the two-electron states on various Fermi surfaces are interpreted.

The physical features of the formation of macroscopic states of superconducting composites consisting of a superconductor and a coating under flux creep are discussed. It is demonstrated that there exist characteristic electric field strengths depending on the properties of the superconductor, cooling conditions, and characteristics of the stabilizing coating, which affect the intensity of the E-I characteristics of the superconducting composites. Analysis shows that the measurements of the critical properties of superconductors can be accompanied by a nonuniform electric field distribution over the composite cross section and high stable superheating of the superconductor, which do not lead to superconductivity breaking.