Two-equation model for supersonic flows based on modelling of pressure–strain correlation

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.A new turbulence model K-ε-Vn for high-speed compressible flows is developed. It is based on modelling of the rapid part of pressure-strain correlation depending on Mach number and on the assumption that the velocity fluctuations normal to streamline play a key role in turbulent mixing process. Simulations of a plane supersonic mixing layers and of axisymmetrical high-speed jets are performed and comparison with the experimental data shows reasonable agreement.dc201

Computation of gas and multiphase supersonic jets with non-equilibrium processes

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.A computational model for simulation of compressible multiphase supersonic jets with non-equilibrium physical and chemical processes is developed. Compared with the others, this model is distinguishes by an extended system of nonequilibrium chemical reactions while taking into account the multiphase non-equilibrium. Lagrangian particle methodology was used. The particle phase change is simulated kinetically and included two solid Al2O3 crystalline structures: meta stable gamma and stable alpha forms. The simulation results were compared with the available results of the other authors. There was a satisfactory agreement regarding the results of the main gaseous component concentrations. Comparison of the simulation results with experimental data also showed their satisfactory agreement.dc201

Modeling high-speed reacting flows with variable turbulent Prandtl and Schmidt numbers

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.A turbulence model that considers the impact of compressibility effects on turbulence and allows for the calculation of the variable turbulent Prandtl (PrT) and Schmidt (ScT) numbers as part of the solution is presented. The model is based on modeling the slow part of pressure/scalar-gradient correlation depending on characteristic time of scalar variable fluctuations (the ratio of scalar variable variance to its dissipation rate) and on the assumption that the velocity fluctuations directed normal to the streamlines play a key role in turbulent mixing process. For the validation of the code the described numerical procedures are applied to a series of jet flow problems. These include supersonic turbulent jets of variable composition and high-speed chemically reacting coflows.dc201

First Measurement of pi e -> pi e gamma Pion Virtual Compton Scattering

Pion Virtual Compton Scattering (VCS) via the reaction pi e --> pi e gamma was observed in the Fermilab E781 SELEX experiment. SELEX used a 600 GeV/c pi- beam incident on target atomic electrons, detecting the incident pi- and the final state pi-, electron and gamma. Theoretical predictions based on chiral perturbation theory are incorporated into a Monte Carlo simulation of the experiment and are compared to the data. The number of reconstructed events (9) and their distribution with respect to the kinematic variables (for the kinematic region studied) are in reasonable accord with the predictions. The corresponding pi- VCS experimental cross section is sigma=38.8+-13 nb, in agreement with the theoretical expectation sigma=34.7 nb.Comment: 10 pages, 12 figures, 4 tables, 25 references, SELEX home page is http://fn781a.fnal.gov/, revised July 21, 2002 in response to journal referee Comment

Effect of optical processing on the surface structure of paratellurite single crystals

The effect of optical treatment of the surfaces of a paratellurite single crystal corresponding to the (100), (110), and (001) crystallographic planes was studied. Using a NanoMap WLI1000 optical profilometer, the relief layer of the sample surface (paratellurite single crystal) was controlled. To study the influence of the polishing method, the process was carried out using three techniques – neutral polishing, acid polishing and alkaline polishing. The characteristics of paratellurite surfaces after grinding and polishing are determined. Conclusions are drawn about the predominant use of polishing with chemical reagents. The anisotropy of surfaces differing in crystallographic directions on the speed of grinding and polishing and on the characteristics of the surfaces is shown. Studies of the structure of ground and polished surfaces corresponding to crystallographic planes have shown that the maximum roughness height is observed for the (001) plane. The smoothest surface is achieved for surfaces coinciding with the crystallographic plane (110)

Correlation effects in the trapping problem: rigorous results in one dimension

Expanded version of a short report presented at the XIth International Congress of Mathematical Physics, Paris, 18-23 July 1994. (Lecture delivered by L.V. Bogachev)Consiglio Nazionale delle Ricerche (CNR). Biblioteca Centrale / CNR - Consiglio Nazionale delle RichercheSIGLEITItal