Heterogeneous plasma from a combined discharge in a vortex argon + steam mixture flow with aluminum particles in the tube of a plasma vortex reactor is experimentally studied. The discharge, plasma and working flow parameters are measured, and the coefficient of energy conversion in the plasma vortex reactor is measured. The electron temperature, the rotational and vibrational temperatures of excited molecular complexes, the temperature of metallic clusters, and the plasma electron concentration are estimated by spectral methods. A kinetic system for calculating the working regimes in the reactor using a discharge in steam with aluminum particles is proposed. A vortex pure steam flow with aluminum particles in the presence of a heating source is numerically modelled. The spatial-temporal distributions of the flow parameters, such as velocity, temperature, and pressure, are obtained together with the molar concentration distributions of the discharge mixture components.

We present a study of disorder origination and growth inside an ordered phase processes induced by the presence of multiplicative noise within mean-field approximation. Our research is based on the study of solutions of the nonlinear self-consistent Fokker-Planck equation for a stochastic spatially extended model of a chemical reaction. We carried out numerical simulation of the probability distribution density dynamics and statistical characteristics of the system under study for varying noise intensity values and system parameter values corresponding to a spatially inhomogeneous ordered state in a deterministic case. Physical interpretation of the results obtained that determines the scenario of noise-induced order–disorder transition is given. Mean-field results are compared with numerical simulations of the evolution of the model under study. We find that beginning from some value of external noise intensity the “embryo” of disorder appears inside the ordered phase. Its lifetime is finite, and it increases with growth of noise intensity. At some second noise intensity value the ordered and disordered phases begin to alternate repeatedly and almost periodically. The frequency of intermittency grows with the increasing of noise intensity. Ordered and disordered phase intermittency affects the process of spatial pattern formation as a consequent change of spatial inhomogeneity configurations.

Numerical simulation of the turbulent three-dimensional swirling flow in experimentally tested plasma vortex reactor were carried out to ascertain that earlier limited modelling properly represents flow phenomena and to provide further insights into use of such apparatus. Exact experimental geometry, electrode location that maximizes energy utilization in accordance with previous research, model heat source, and reduced mixture composition (pure Ar) were used. A qualitative agreement between the results of the calculations and the experimental data for pure argon has been obtained. Structure of counterflow zone, crucial for energy extraction, and corresponding temperature field are presented.

The absolute instability of a Rankine vortex with an axial flow and paraxial heat source is investigated. The dispersion relation for vortex modes is derived analytically. The dependence of dispersion properties of the media on control parameters such as swirl parameter S, velocity a, and heat source power (density parameter Q) is studied. The frequency of helical waves increases and the increment decreases with increasing heat source power, accompanied by a decrease in the width of the neutral stability region. Numerical analysis also suggests that one of the dispersion curve branches could include an instability region of a parametric nature.

The influence of an external random field on the competition process in a nonlinear open spatially extended system is analyzed numerically. A three-component model is chosen as the competition model in which a "weak" species can move in space and the rate of the resource density growth fluctuates in space and in time [A.S. Mikhailov and I.V. Uporov, Usp. Sov. Phys. Usp. 27, 695 (1984)]. It is demonstrated that in addition to the noise-induced statistically steady state found by the authors [Sov. Phys. Usp. 27, 695 (1984)], in which both species can coexist, there exists another noise-induced statistically steady state, in which the "weak" species displaces the "strong" species, i.e. the "strong" species at an average asymptotically disappears.

НЕЛИНЕЙНОЕ МНОГОМЕРНОЕ УРАВНЕНИЕ ФОККЕРА-ПЛАНКА В ПРИБЛИЖЕНИИ СРЕДНЕГО

Spatial pattern formation in fluctuating media is researched analytically from the point of view of the order parameters concept. A reaction-diffusion system with external noise is considered as a model of such media. Stochastic equations for unstable mode amplitudes (order parameters), the dispersion equation for averaged amplitudes of unstable modes, and the Fokker-Planck equation for the order parameters are obtained. The theory developed makes it possible to analyze different noise-induced effects including the variation of boundaries of ordering and disordering phase transitions depending on the parameters of external noise.

Исследовано влияние мультипликативных флуктуаций параметров системы на образование диссипативных структур при возникновении неустойчивости типа мягкой моды в системах хищник -жертва на примере модели Шеффера