arXiv subjects

Roman V. Maltsev

Publications and source records attributed to Roman V. Maltsev.

3 recordsLinked to original sources

arXiv2012

Employing per-component time step in DSMC simulations of disparate mass and cross-section gas mixtures

A new approach to simulation of stationary flows by Direct Simulation Monte Carlo method is proposed. The idea is to specify an individual time step for each component of a gas mixture. The approach consists of modifications mainly to collision phase and recommendation on choosing time step ratios. It allows softening the demands on the computational resources for cases of disparate collision diameters of molecules and/or disparate molecular masses. These are the cases important in vacuum deposition technologies. Few tests of the new approach are made. Finally, the usage of new approach is demonstrated on a problem of silver nanocluster diffusion in carrier gas argon in conditions of silver deposition experiments.

physics.comp-ph↗

arXiv2012

Numerical study of gas dynamic processes in conditions of silver nanocluster deposition experiments

In this paper, experiments on the deposition of silver nanoclusters are analysed numerically using improved DSMC method. These experiments were made in the Institute of Thermophysics SB RAS recent years, in the context of the development of bactericidal nanocomposite coatings deposition technology. In this paper we analyze the gas-dynamic effects in experimental conditions: the parameters of the gas stream from the silver vapor source, the flow of silver vapors inside the source and in the outflowing jet under different conditions, the movement of silver nanoclusters of different masses (up to 1024 atoms) in buffer gas, expecting different places of nanocluster formation in a source. The simulations revealed a strong nonisothermal state of the source, which was later confirmed experimentally, the site of nanocluster nulceus formation in a source (subcooled confuser of the nozzle) and, finally, show that the process of nucleation of nanoclusters inside a source is of heterogeneous nature. The width of the silver nanocluster jet (of mass 1024 atoms) reaching target according to sumulations, is in good agreement with that obtained in the experiment coating profile on the target substrate in a form of narrow strip made of stainless steel, that further validates the numerical simulations.

cond-mat.other↗

arXiv2012

Improved Direct Simulation Monte Carlo method for solving modern problems of rarefied gases dynamics

First of all, this paper presents some improvements of DSMC method in the form of new schemes and approaches, that, for a wide class of problems, increase performance and reduce the demands on computer resources. The most important improvement is the scheme of temporal factors, allowing the use of different time step for different sorts of particles, thus reducing the complexity and/or resource usage in simulation of stationary problems with very different collisional cross-sections between components of a mixture. Other improvements include the similarity parameter for efficient estimation of the number of simulational particles required for 1D, 2D and 3D computations, the new scheme for solving axisymmetric problems, an approach to detect and reject repetitive collisions. Also, some advice on technical optimization of algorithm for modern computers is offered.

physics.flu-dyn↗