V. N. Emelyanov

Comparison of Convective Flux Discretization Schemes in Detached-Eddy Simulation of Turbulent Flows on Unstructured Meshes

Detached-eddy simulation (DES) of turbulent flows of viscous incompressible fluid is performed based on unstructured meshes. The common finite-difference schemes for discretization of convective fluxes are applied, and the DES model constants are calibrated for each of the numerical schemes presented. Results computed with the DES model on various types of meshes (block-structured, tetrahedral and polyhedral unstructured meshes, as well as a mesh with triangular prismatic elements) are analyzed. Efficiency of the discretization schemes selected for DES calculations is compared for different meshes. Calculations are performed for some benchmark test cases, decaying homogeneous isotropic turbulence and flow behind a backward-facing step. Recommendations to the selection of model constants and properties of various meshes are given for the DES calculations of turbulent flows of viscous incompressible fluid.

Numerical simulation of the interaction of a transverse jet with a supersonic flow using different turbulence models

This paper presents a numerical simulation of the flow resulting from transverse jet injection into a supersonic flow through a slot nozzle at different pressures in the injected jet and the crossflow. Calculations on grids with different resolutions use the Spalart–Allmaras turbulence model, the k–ε model, the k–ω model, and the SST model. Based on a comparison of the calculated and experimental data on the wall pressure distribution, the length of the recirculation area, and the depth of jet penetration into the supersonic flow, conclusions are made on the accuracy of the calculation results for the different turbulence models and the applicability of these models to similar problems.

Interaction of laser pulse with liquid droplet

Interaction of laser pulse with gas-droplet mixtures plays an important role in different applications including environmental monitoring of high-risk industrial objects and enclosed spaces, laser ignition of volumetric explosion for application to fire mitigation and design of air-breathing pulse detonation engines. The role of droplets in environmental and engineering applications is two-fold. On the one hand, droplets may pose potential hazard for human activity (erosion of surface and deposition of aerosols in human lungs). On the other hand, they can be successfully used in engineering solutions (to induce working processes in energy systems and to suppress acoustic instabilities of thermal processes). Processes that control transport and combustion of droplets remain unresolved, and introduce significant uncertainties into modeling and simulation. For the optimization of technological processes and for keeping the environment free from droplets, a detailed knowledge of the interaction of laser pulse with individual droplets is necessary.

Numerical simulation of air hypersonic flows with equilibrium chemical reactions

The finite volume method is applied to solve unsteady three-dimensional compressible Navier–Stokes equations on unstructured meshes. High-temperature gas effects altering the aerodynamics of vehicles are taken into account. Possibilities of the use of graphics processor units (GPUs) for the simulation of hypersonic flows are demonstrated. Solutions of some test cases on GPUs are reported, and a comparison between computational results of equilibrium chemically reacting and perfect air flowfields is performed. Speedup of solution on GPUs with respect to the solution on central processor units (CPUs) is compared. The results obtained provide promising perspective for designing a GPU-based software framework for practical applications.The finite volume method is applied to solve unsteady three-dimensional compressible Navier–Stokes equations on unstructured meshes. High-temperature gas effects altering the aerodynamics of vehicles are taken into account. Possibilities of the use of graphics processor units (GPUs) for the simulation of hypersonic flows are demonstrated. Solutions of some test cases on GPUs are reported, and a comparison between computational results of equilibrium chemically reacting and perfect air flowfields is performed. Speedup of solution on GPUs with respect to the solution on central processor units (CPUs) is compared. The results obtained provide promising perspective for designing a GPU-based software framework for practical applications.

Simulation of the Transverse Injection of a Pulsed Jet from the Surface of a Flat Plate into a Supersonic Flow

The transverse injection of a pulsed jet into a supersonic flow for thrust vectoring in solid rocket motors is investigated. The gas flow through the injection nozzle is controlled by a piston which performs reciprocating motion. Reynolds-averaged Navier–Stokes equations and the (k–ε) turbulence model equations are discretized using the finite volume method and moving grids. The pressure distributions on the plate surface obtained using various approaches to the description of the flow field and difference schemes are compared. The solution obtained for the case of injection of a pulsed jet is compared with the solution for the case where a valve prevents gas flow through the injection nozzle. The dependence of the control force produced by gas injection on time is investigated.

Large-eddy simulation of turbulence-induced aero-optic effects in free shear flows

Formation, interaction and destruction of coherent structures play an important role in the propagation of the coherent beam through the environment and the occurrence of optical aberrations. The issues related to modeling and simulation of aero-optical effects in a free mixing layer and free round turbulent jet are considered. A semi-empirical model is developed to study the distortion of the phase function of the coherent beam, induced by turbulent flow fluctuations. Large-eddy simulation of free shear flows is performed. The results computed with the semi-empirical model and numerical results are compared with the experimental data and data computed with the Reynolds-averaged Navier–Stokes equations. The results obtained are beneficial for design and optimization of systems based on coherent optical adaptive technique.