scholarly journals The Knudsen Paradox in Micro-Channel Poiseuille Flows with a Symmetric Particle

2020 ◽  
Vol 11 (1) ◽  
pp. 351
Author(s):  
Ananda Subramani Kannan ◽  
Tejas Sharma Bangalore Narahari ◽  
Yashas Bharadhwaj ◽  
Andreas Mark ◽  
Gaetano Sardina ◽  
...  
Keyword(s):  
Flow Behavior ◽  
Direct Simulation Monte Carlo ◽  
Micro Channel ◽  
Confined Geometries ◽  
Rarefied Flows ◽  
Model Pore ◽  
Duct Geometry ◽  
Transport Effects ◽  
Non Local ◽  
Simulation Monte Carlo

The Knudsen paradox—the non-monotonous variation of mass-flow rate with the Knudsen number—is a unique and well-established signature of micro-channel rarefied flows. A particle which is not of insignificant size in relation to the duct geometry can significantly alter the flow behavior when introduced in such a system. In this work, we investigate the effects of a stationary particle on a micro-channel Poiseuille flow, from continuum to free-molecular conditions, using the direct simulation Monte-Carlo (DSMC) method. We establish a hydrodynamic basis for such an investigation by evaluating the flow around the particle and study the blockage effect on the Knudsen paradox. Our results show that with the presence of a particle this paradoxical behavior is altered. The effect is more significant as the particle becomes large and results from a shift towards relatively more ballistic molecular motion at shorter geometrical distances. The need to account for combinations of local and non-local transport effects in modeling reactive gas–solid flows in confined geometries at the nano-scale and in nanofabrication of model pore systems is discussed in relation to these results.

Modelling of chemical reactions in hypersonic rarefied flow with the direct simulation Monte Carlo method

1996 ◽  
Vol 312 ◽  
pp. 149-172 ◽  
Author(s):  
Michael A. Gallis ◽  
John K. Harvey
Keyword(s):  
Monte Carlo ◽  
Chemical Reactions ◽  
Energy Exchange ◽  
Chemical Reactivity ◽  
Direct Simulation Monte Carlo ◽  
Direct Simulation ◽  
Rarefied Flow ◽  
Rarefied Flows ◽  
Exchange Processes ◽  
Simulation Monte Carlo

In this paper the phenomenon of chemical reactivity in hypersonic rarefied flows is examined. A new model is developed to describe the reactions and post-collision energy exchange processes that take place under conditions of molecular non-equilibrium. The new scheme, which is applied within the framework of the direct simulation Monte Carlo (DSMC) method, draws its inspiration from the principles of maximum entropy which were developed by Levine & Bernstein. Sample hypersonic flow fields, typical of spacecraft re-entry conditions in which reactions play an important role, are presented and compared with results from experiments and other DSMC calculations. The latter use traditional methods for the modelling of chemical reactions and energy exchange. The differences are discussed and evaluated.

Non-equilibrium thermal transport and entropy analyses in rarefied cavity flows

2019 ◽  
Vol 864 ◽  
pp. 995-1025 ◽  
Author(s):  
Vishnu Venugopal ◽  
Divya Sri Praturi ◽  
Sharath S. Girimaji
Keyword(s):  
Thermal Transport ◽  
Direct Simulation Monte Carlo ◽  
Kinetic Scheme ◽  
Driven Cavity ◽  
Rarefied Flows ◽  
Flow Simulations ◽  
Extended Thermodynamic ◽  
Simulation Monte Carlo ◽  
Mach Numbers ◽  
Non Equilibrium

Thermal transport in rarefied flows far removed from thermodynamic equilibrium is investigated using kinetic-theory-based numerical simulations. Two numerical schemes – unified gas kinetic scheme (UGKS) and direct simulation Monte Carlo (DSMC) – are employed to simulate transport at different degrees of rarefaction. Lid-driven cavity flow simulations of argon gas are performed over a range of Knudsen numbers, Mach numbers and cavity shapes. Thermal transport is then characterized as a function of lid Mach number and Knudsen number for different cavity shapes. Vast deviations from the Fourier law – including thermal transport aligned along the direction of temperature gradient – are observed. Entropy implications are examined using Sackur–Tetrode and Boltzmann $H$-theorem formulations. At low Knudsen and Mach numbers, thermal transport is shown to be amenable to both entropy formulations. However, beyond moderate Knudsen and Mach numbers, thermal transport complies only with the Boltzmann $H$-theorem entropy statement. Two extended thermodynamic models are compared against simulation data and found to account for some of the observed non-equilibrium behaviour.

Unified Gas Kinetic Scheme and Direct Simulation Monte Carlo Computations of High-Speed Lid-Driven Microcavity Flows

2015 ◽  
Vol 17 (5) ◽  
pp. 1127-1150 ◽  
Author(s):  
Vishnu Venugopal ◽  
Sharath S. Girimaji
Keyword(s):  
Monte Carlo ◽  
High Speed ◽  
Direct Simulation Monte Carlo ◽  
Kinetic Scheme ◽  
Cavity Flow ◽  
Direct Simulation ◽  
Driven Cavity ◽  
Rarefied Flows ◽  
Simulation Monte Carlo ◽  
Unified Gas Kinetic Scheme

AbstractAccurate simulations of high-speed rarefied flows present many physical and computational challenges. Toward this end, the present work extends the Unified Gas Kinetic Scheme (UGKS) to a wider range of Mach and Knudsen numbers by implementing WENO (Weighted Essentially Non-Oscillatory) interpolation. Then the UGKS is employed to simulate the canonical problem of lid-driven cavity flow at high speeds. Direct Simulation Monte Carlo (DSMC) computations are also performed when appropriate for comparison. The effect of aspect ratio, Knudsen number and Mach number on cavity flow physics is examined leading to important insight.

Flow behavior of clusters in a riser simulated by direct simulation Monte Carlo method

2005 ◽  
Vol 106 (3) ◽  
pp. 197-211 ◽  
Author(s):  
Wang Shuyan ◽  
Liu Huanpeng ◽  
Lu Huilin ◽  
Liu Wentie ◽  
Jiamin Ding ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Flow Behavior ◽  
Direct Simulation Monte Carlo ◽  
Direct Simulation ◽  
Simulation Monte Carlo

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

2003 ◽  
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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