The gas flow diode effect: theoretical and experimental analysis of moderately rarefied gas flows through a microchannel with varying cross section

Abstract The present study investigates the flow behavior of the rarefied gas over a wall-mounted cube. The problem is studied for different cube heights (h) of 9mm and 18mm in the slip and transition regimes. The Direct Simulation Monte Carlo (DSMC) method is employed to evaluate the properties such as velocity, pressure and temperature fields. The Reynolds number (Re) ranges from 403 to 807, and the Knudsen number (Kn) is in the range from 0.05 to 0.103. A typical shock wave is formed in front of the cube. The recirculation length of the vortices normalized with respect to the respective cube heights for Kn = 0.05 and Kn = 0.103 are about 1.11 and 1.95 respectively. Similarly, the center of the vortices is located at about 3.33 and 6.11 times the respective cube heights upstream, for Kn = 0.05 and Kn = 0.103. The local temperature and pressure variations observed upstream of the cube are two orders higher in magnitude and are primarily attributed to strong compressibility effects. The present study paves the way for benchmarking, and forms a basis for understanding the rarefied gas flows over complex geometries.

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An extended macroscopic transport model for rarefied gas flows in long capillaries with circular cross section

Physics of Fluids ◽

10.1063/1.3500681 ◽

2010 ◽

Vol 22 (11) ◽

pp. 112004 ◽

Cited By ~ 18

Author(s):

Peyman Taheri ◽

Henning Struchtrup

Keyword(s):

Cross Section ◽

Rarefied Gas ◽

Transport Model ◽

Circular Cross Section ◽

Gas Flows ◽

Rarefied Gas Flows

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Efficient Deterministic Modelling of Three-Dimensional Rarefied Gas Flows

Communications in Computational Physics ◽

10.4208/cicp.220111.140711a ◽

2012 ◽

Vol 12 (1) ◽

pp. 162-192 ◽

Cited By ~ 50

Author(s):

V. A. Titarev

Keyword(s):

Gas Flow ◽

Parallel Machines ◽

High Efficiency ◽

Rarefied Gas ◽

Three Dimensional ◽

Collision Integral ◽

Gas Flows ◽

Rarefied Gas Flows ◽

Deterministic Modelling ◽

Model Collision

AbstractThe paper is devoted to the development of an efficient deterministic framework for modelling of three-dimensional rarefied gas flows on the basis of the numerical solution of the Boltzmann kinetic equation with the model collision integrals. The framework consists of a high-order accurate implicit advection scheme on arbitrary unstructured meshes, the conservative procedure for the calculation of the model collision integral and efficient implementation on parallel machines. The main application area of the suggested methods is micro-scale flows. Performance of the proposed approach is demonstrated on a rarefied gas flow through the finite-length circular pipe. The results show good accuracy of the proposed algorithm across all flow regimes and its high efficiency and excellent parallel scalability for up to 512 cores.

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Investigation of Subsonic and Hypersonic Rarefied Gas Flow Over a Backward Facing Step

10.31219/osf.io/ck7ag ◽

2019 ◽

Author(s):

Deepak Nabapure ◽

Jayesh Sanwal ◽

Sreeram Rajesh ◽

K Ram Chandra Murthy

Keyword(s):

Mach Number ◽

Gas Flow ◽

Rarefied Gas ◽

Flow Characteristics ◽

Direct Simulation Monte Carlo ◽

Primary Objective ◽

Gas Flows ◽

Backward Facing Step ◽

Rarefied Gas Flows ◽

Velocity Pressure

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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Direct Simulation Monte Carlo Analysis of Rarefied Gas Flow Structures and Ventilation of Etching Gas in Magneto-Microwave Plasma Etching Reactors

Journal of Fluids Engineering ◽

10.1115/1.1459074 ◽

2002 ◽

Vol 124 (2) ◽

pp. 476-482 ◽

Cited By ~ 1

Author(s):

Masato Ikegawa ◽

Yoshihumi Ogawa ◽

Ryoji Fukuyama ◽

Tatehito Usui ◽

Jun’ichi Tanaka

Keyword(s):

Plasma Etching ◽

Gas Flow ◽

Microwave Plasma ◽

Rarefied Gas ◽

Direct Simulation Monte Carlo ◽

Gas Flows ◽

Direct Simulation ◽

Rarefied Gas Flows ◽

Simulation Monte Carlo ◽

Gas Supply

Gas flows in plasma etching reactors for semiconductor fabrication became a chief consideration in designing second-generation reactors with higher etching rates. An axisymmetrical model based on the direct simulation Monte Carlo method has been developed for analyzing rarefied gas flows in a vacuum chamber with the conditions of downstream pressure and gas flow rate. By using this simulator, rarefied gas flows with radicals and etch-products were calculated for microwave-plasma etching reactors. The results showed that the flow patterns in the plasma chamber strongly depend on the Knudsen number and the gas-supply structure. The ventilation of the etch-products in the plasma chamber was found to be improved both for higher Knudsen numbers and for gas-supply structures of the downward-flow type, as compared with those of the radial-flow or upward-flow types.

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Analytical models of unstable rarefied gas flow in channels and nozzles: simulation and comparison

Progress in Propulsion Physics – Volume 11 ◽

10.1051/eucass/201911613 ◽

2019 ◽

Author(s):

O.A. Aksenova ◽

I.A. Khalidov

Keyword(s):

Gas Flow ◽

Rarefied Gas ◽

Chaotic Behavior ◽

Nonlinear Dynamic System ◽

Analytical Models ◽

Gas Flows ◽

Flow Conditions ◽

Practical Applications ◽

Rarefied Gas Flows ◽

Montecarlo Method

Three different analytical models of unstable rarefied gas flows in channels and nozzles are compared using numerical simulations by MonteCarlo method. Numerical results have demonstrated the chaotic behavior of constructed nonlinear dynamic system and the limit properties of corresponding trajectories, attractors, and bifurcations of rarefied gas flows in channels. Flow conditions satisfying the experimental requirements are indicated where the instability of considered type can be detected. The advantages and the drawbacks of the considered approximations are detected and the features of obtained solutions are indicated. Recommendations are given for applying the results in practical applications and in numerical calculations of rarefied gas flows.

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New exact solutions for microscale gas flows

Journal of Engineering Mathematics ◽

10.1007/s10665-021-10135-1 ◽

2021 ◽

Vol 128 (1) ◽

Author(s):

Hollis Williams

Keyword(s):

Heat Source ◽

Exact Solutions ◽

Gas Flow ◽

Rarefied Gas ◽

Gas Flows ◽

Point Heat Source ◽

Slip Boundary ◽

Rarefied Gas Flows ◽

New Exact Solutions ◽

Dependent Point

AbstractWe present a number of exact solutions to the linearised Grad equations for non-equilibrium rarefied gas flows and heat flows. The solutions include the flow and pressure fields associated to a point force placed in a rarefied gas flow close to a no-slip boundary and the temperature field for a point heat source placed in a heat flow close to a temperature jump boundary. We also derive the solution of the unsteady Grad equations in one dimension with a time-dependent point heat source term and the Grad analogue of the rotlet, a well-known singularity of Stokes flow which corresponds to a point torque.

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