Study of Transitional Regime Gas Flows over a Backward Facing Step

In the present study the Direct Simulation Monte Carlo (DSMC) method, which is one of most the widely used numerical methods to study the rarefied gas flows, is applied to investigate the flow characteristics of a hypersonic and subsonic flow over a backward-facing step. The work is driven by the interest in exploring the effects of the Mach number on the flow behaviour. The primary objective of this paper is to study the variation of velocity, pressure, and temperature with Mach number. The numerical tool is validated with well-established results from the literature and a good agreement is found among them. The flow is analyzed and some comments on the characteristics of the flow are also added.

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Examination of the LBM in Simulation of Microchannel Flow in Transitional Regime

1st International Conference on Microchannels and Minichannels ◽

10.1115/icmm2003-1048 ◽

2003 ◽

Cited By ~ 1

Author(s):

Ching Shen ◽

Dong-Bo Tian ◽

Chong Xie ◽

Jing Fan

Keyword(s):

Direct Simulation Monte Carlo ◽

Channel Flows ◽

Transitional Flow ◽

Gas Flows ◽

Micro Channel ◽

Transitional Regime ◽

Micro Electro Mechanical Systems ◽

Information Preservation ◽

Simulation Monte Carlo ◽

Boltzmann Method

Gas flows in micro-electro-mechanical systems (MEMS) owing to the small size of the systems possess a relatively large Knuden number and usually belong to the slip and transitional flow regimes. This paper employs three schemes, namely the direct simulation Monte Carlo (DSMC) method, information preservation (IP) method, and the lattice Boltzmann method (LBM), to simulation micro-channel flows at three Knudsen numbers (Kn) of 0.0194, 0.194 and 0.388. The present LBM results are in agreement with those given by Nie et al. (2002), whereas they significantly differ from the DSMC (and IP) results as Kn increases. This suggests that the present version of LBM is not feasible to simulate the micro-channel flows in transition regime.

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Sidewall effects on heat transfer in narrow backward facing step in transitional regime

Numerical Heat Transfer Part A Applications ◽

10.1080/10407782.2019.1644930 ◽

2019 ◽

Vol 76 (8) ◽

pp. 628-647

Author(s):

G. L. Juste ◽

L. Sánchez de León ◽

E. López-Núñez ◽

P. Fajardo

Keyword(s):

Heat Transfer ◽

Backward Facing Step ◽

Transitional Regime ◽

Sidewall Effects

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In Situ Observation of Catalyzed Gasification of Graphite by Nickel

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100097090 ◽

1981 ◽

Vol 39 ◽

pp. 76-77

Author(s):

R. T. K. Baker ◽

R. D. Sherwood

Keyword(s):

Objective Lens ◽

In Situ Observation ◽

Gas Flows ◽

Catalytic Gasification ◽

Television Camera ◽

Viewing Screen ◽

Fuels And Chemicals ◽

Gasification Of Carbon ◽

Transmission Microscope

The catalytic gasification of carbon at high temperature by microscopic size metal particles is of fundamental importance to removal of coke deposits and conversion of refractory hydrocarbons into fuels and chemicals. The reaction of metal/carbon/gas systems can be observed by controlled atmosphere electron microscopy (CAEM) in an 100 KV conventional transmission microscope. In the JEOL gas reaction stage model AGl (Fig. 1) the specimen is positioned over a hole, 200μm diameter, in a platinum heater strip, and is interposed between two apertures, 75μm diameter. The control gas flows across the specimen and exits through these apertures into the specimen chamber. The gas is further confined by two apertures, one in the condenser and one in the objective lens pole pieces, and removed by an auxiliary vacuum pump. The reaction zone is <1 mm thick and is maintained at gas pressure up to 400 Torr and temperature up to 1300<C as measured by a Pt-Pt/Rh 13% thermocouple. Reaction events are observed and recorded on videotape by using a Philips phosphor-television camera located below a hole in the center of the viewing screen. The overall resolution is greater than 2.5 nm.

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