Investigation of basic molecular gas structural effects on hydrodynamics and thermal behaviors of rarefied shear driven micro/nano flow using DSMC

Ejtehadi, Omid; Roohi, Ehsan; Esfahani, Javad Abolfazli

doi:10.1016/j.icheatmasstransfer.2012.01.010

Cited by 42 publications

(8 citation statements)

References 21 publications

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“…An improved version of Bird's DS]VIC-2D code which had already employed by the authors for different micro/nanoflow application, see Refs. [17][18][19][20][21][22], is used and the SBT and MFS collision schemes are implemented in. In this work, molecular interactions is modeled by variable hard sphere (VHS) model and monatomic argon, m = 6.63x 10"^* Kg and d = 4.ll X 10~'° m is considered as the gaseous medium.…”

Section: Resultsmentioning

confidence: 99%

DSMC Simulation of Low Knudsen Micro/Nanoflows Using Small Number of Particles per Cells

Amiri-Jaghargh¹,

Roohi²,

Niazmand

et al. 2013

Journal of Heat Transfer

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Direct simulation Monte Carlo (DSMC) method in low Knudsen rarefied flows at micro/ nanoscales remains a big challenge for researchers due to large computational requirements. In this article, the application of the simplified Bernoulli-trials (SBT)ldual grid collision scheme is extended for solving low Knudsenltow speed and low Knudsenlhigh gradient rarefied microlnanoflows. The main advantage of the SBT algorithm is to provide accurate calculations using much smaller number of particles per cell, i.e., (N) « 2, which is quite beneficial for near continuum DSMC simulations where the requirement of fine meshes faces the simulation with serious memory restrictions. Comparing the results of the SBTIdual grid scheme with the no time counter (NTC) scheme and majorant frequency scheme (MFS), it is shown that the SBTIdual grid scheme could successfully predict the thermal pattern and hydrodynamics field as well as surface parameters such as velocity slip, temperature jump and wall heat fluxes. Therefore, we present SBTIdual grid algorithm as a suitable alternative of the standard collision schemes in the DSMC method for typical microlnanoflows solution. Nonlinear flux-corrected transport (FCT) algorithm is also employed as a filter to extract the smooth solution from the noisy DSMC calculation for low speed/low Knudsen number DSMC calculations.

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Section: Resultsmentioning

confidence: 99%

DSMC Simulation of Low Knudsen Micro/Nanoflows Using Small Number of Particles per Cells

Amiri-Jaghargh¹,

Roohi²,

Niazmand

et al. 2013

Journal of Heat Transfer

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“…Using our experience in developing different continuum [30][31][32][33][34][35][36] and stochastic particle [37][38][39][40][41][42][43][44] solvers, we extend our hybrid DSMC-NS frame in the context of OpenFOAM [45]. The NS solver implements the velocity slip and the temperature jump boundary conditions at the solid walls, where they are required.…”

Section: Introductionmentioning

confidence: 99%

A hybrid DSMC/Navier–Stokes frame to solve mixed rarefied/nonrarefied hypersonic flows over nano‐plate and micro‐cylinder

Darbandi

Roohi

2013

Numerical Methods in Fluids

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SUMMARYWe extend a hybrid DSMC/Navier–Stokes (NS) approach to unify the DSMC and the NS simulators in one framework capable of solving the mixed non‐equilibrium and near‐equilibrium flow regions efficiently. Furthermore, we use a one‐way state‐based coupling (Dirichlet–Dirichlet boundary‐condition coupling) to transfer the required information from the continuum region to the rarefied one. The current hybrid DSMC–NS frame is applied to the hypersonic flows over nanoflat plate and microcylinder cases. The achieved solutions are compared with the pure DSMC and NS solutions. The results show that the current hybrid approach predicts the surface heat transfer rate and shear stress magnitudes very accurately. Some important conclusions can be drawn from this study. For example, although the shock wave region would be a non‐equilibrium region, it is not necessary to use a pure DSMC simulator to solve it entirely. This is important when the researchers wish to predict the surface properties such as velocity slip, temperature jump, wall heat flux rate, and friction drag magnitudes accurately. Our investigation showed that our hybrid solution time would be at least 40% (for the flat plate) and 35% (for the cylinder) of the time that must be spent by a pure DSMC solver to attain the same accuracy.Copyright © 2013 John Wiley & Sons, Ltd.

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“…The authors had already employed the above mentioned DSMC solver in different micro/nano flow applications; see Refs. [12][13][14][15][16]. In this work, molecular interactions are modeled using variable hard sphere (VHS) model and monatomic argon, m=6.63×10 -26 Kg and d=4.17×10 -10 m, is considered as the gaseous medium.…”

Section: Resultsmentioning

confidence: 99%

DSMC simulation of micro/nano flows using SBT-TAS technique

Amiri-Jaghargh¹,

Nami²,

Stefanov³

et al. 2014

AIP Conference Proceedings

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The aim of the current paper is to decrease the required computational time and memory of the direct simulation Monte Carlo (DSMC) method using the simplified Bernoulli-trials (SBT) collision algorithm in combination with the transient adaptive subcell (TAS) technique. It is already shown that SBT collision could provide accurate solutions with a few particles per cell, when the requirement for grid resolution of the pure SBT remains the same as standard DSMC collision algorithms. Here, we demonstrate that the combination of the SBT with the TAS technique could reduce the number of required cells considerably, especially for low Kn micro/nano flows, while the accuracy is preserved and computational time decreases. The efficiency of the SBT-TAS is investigated for two typical test cases, i.e., low Knudsen/low speed flow in micro cavity and high speed/high gradient flow over the nano-scale flat plate. We tested cavity flow at Kn=0.005 and show that SBT-TAS solution using a coarse grid of 50×50 agrees suitably with the NTC solution using a 200×200 cell with 2×2 fixed subcells and number of particles per cell PPC=20 (called correct solution), see Fig. 4, while the computational time of the SBT-TAS decreases by 64%. We show that using of TAS grid movement (SBT-TAS-Dual) decreases the mean collision separation; however, accuracy gain is almost slight compared to the extra computational cost of the grid movement. We will show that product of the local Knudsen number by the average subcells number in a cell is constant. For flow over the flat plate geometry, we will show that even though TAS scheme could provide enough number of collision subcells even for quite coarse grids, the smearing of gradients due to larger sample cell size could deteriorate the final solution.

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Investigation of basic molecular gas structural effects on hydrodynamics and thermal behaviors of rarefied shear driven micro/nano flow using DSMC

Cited by 42 publications

References 21 publications

DSMC Simulation of Low Knudsen Micro/Nanoflows Using Small Number of Particles per Cells

DSMC Simulation of Low Knudsen Micro/Nanoflows Using Small Number of Particles per Cells

A hybrid DSMC/Navier–Stokes frame to solve mixed rarefied/nonrarefied hypersonic flows over nano‐plate and micro‐cylinder

DSMC simulation of micro/nano flows using SBT-TAS technique

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