Showing papers by "Stefan Stefanov published in 2016"
TL;DR: In this paper, the authors present a detailed summary of different collision models developed in the framework of the direct simulation Monte Carlo (DSMC) method, i.e., the simplified Bernoulli trial (SBT), which permits efficient low-memory simulation of rarefied gas flows.
97 citations
TL;DR: In this article, the authors presented a numerical analysis of a novel configuration of Knudsen pump for rarefied gas flow, which consists of two facing isothermal ratchet surfaces at different temperatures.
38 citations
TL;DR: In this article, the authors investigated the flow of a rarefied gas in a square enclosure with one wall at high temperature and the other three walls at the same low temperature and found that along the side walls the gas velocity may be either from cold to hot or from hot to cold regions.
Abstract: The flow of a rarefied gas in a square enclosure with one wall at high temperature and the other three walls at the same low temperature is investigated. The flow, characterized by the reference Knudsen number and ratio of the cold over the hot temperatures, is simulated both deterministically, using the nonlinear Shakhov kinetic model, and stochastically, using the DSMC method. Excellent agreement between the two approaches is obtained. It is found that along the side walls the gas velocity, depending on the flow parameters, may be either from cold to hot or from hot to cold regions. Furthermore, it is confirmed that the average heat flux departing from the hot plate exhibits a nonmonotonic behavior with regard to the temperature ratio, deducing a maximum heat flux at a temperature ratio of about 0.3. The flow and heat transfer characteristics are explained by computing the ballistic and collision parts of the total bulk quantities and by investigating the contribution of each part to the overall solution.
7 citations
Journal Article•
TL;DR: In this paper, the authors present a detailed summary of different collision models developed in the framework of the direct simulation Monte Carlo (DSMC) method, which permits efficient low-memory simulation of rarefied gas flows.
1 citations
15 Nov 2016
TL;DR: In this article, the authors review the accuracy of the Simplified Bernoulli Trial (SBT) algorithm and its variants, i.e., SBT-TAS and ISBT, in simulation of a wide spectrum of rarefied flow problems, including collision frequency ratio evaluation in the equilibrium condition.
Abstract: This paper reviews the accuracy of the Simplified Bernoulli Trial (SBT) algorithm and its variants, i.e., SBT-TAS (SBT on transient adaptive subcells) and ISBT (intelligence SBT) in the simulation of a wide spectrum of rarefied flow problems, including collision frequency ratio evaluation in the equilibrium condition, comparison of the Sonine-polynomial coefficients prediction in the Fourier flow with the theoretical prediction of the Chapman-Enskog expansion, accurate wall heat flux solution for the Fourier flow in the early slip regime, and hypersonic flows over cylinder and biconic geometries. We summarize advantages and requirements that utilization of the SBT collision families brings to a typical DSMC solver.
1 citations
Journal Article•
TL;DR: In this article, an attempt for simultaneous removal of sulphates and nitrates from municipal, agricultural and industrial wastewaters by oxidation of the sulphides to sulphates, and reduction of the nitrates to nitrogen in electrochemical way is made.
Abstract: This study is an attempt for simultaneous removal of sulphates and nitrates from municipal, agricultural and industrial wastewaters by oxidation of the sulphides to sulphates and reduction of the nitrates to nitrogen in electrochemical way. The processes are carried out in newly designed fuel cells and as a result energy is released which can be used. The aim of the work is to improve the energy efficiency of the fuel cell by minimizing internal losses by optimizing the material, design and position of the electrodes.