Nonequilibrium Gas Flow and Heat Transfer in a Heated Square Microcavity

Tatsios, Giorgos; Vargas, Manuel; Stefanov, Stefan; Valougeorgis, Dimitris

doi:10.1080/01457632.2015.1111079

Cited by 9 publications

(10 citation statements)

References 24 publications

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“…The authors claim that at small pressures the rate of reduction of the first flow is larger than the rate of increase of the second one and therefore the total flow must initially decrease with pressure. A further increase in pressure stimulates the overall drift velocity that in turn, from that point on, monotonically increases the entire flow through the tube.Recently, the concept of decomposing the solution into two parts, as described above, has been accordingly implemented in the typical DSMC algorithm by introducing a suitable particle indexation process [21,22]. In the present work the same DSMC decomposition is implemented to investigate the Knudsen paradox in a precise manner with quantitative arguments.…”

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confidence: 98%

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Predicting the Knudsen paradox in long capillaries by decomposing the flow into ballistic and collision parts

2015

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The well-known Knudsen paradox observed in pressure driven rarefied gas flows through long capillaries is quantitatively explored by decomposing the particle distribution function into its ballistic and collision parts. The classical channel, tube, and duct Poiseuille flows are considered. The solution is obtained by a typical direct simulation Monte Carlo algorithm supplemented by a suitable particle decomposition indexation process. It is computationally confirmed that in the free-molecular and early transition regimes the reduction rate of the ballistic flow is larger than the increase rate of the collision flow deducing the Knudsen minimum of the overall flow. This description interprets in a precise, quantitative manner the appearance of the Knudsen minimum and verifies previously reported qualitative physical arguments.

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confidence: 98%

“…Recently, the concept of decomposing the solution into two parts, as described above, has been accordingly implemented in the typical DSMC algorithm by introducing a suitable particle indexation process [21,22]. In the present work the same DSMC decomposition is implemented to investigate the Knudsen paradox in a precise manner with quantitative arguments.…”

mentioning

confidence: 98%

Predicting the Knudsen paradox in long capillaries by decomposing the flow into ballistic and collision parts

2015

Self Cite

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“…Such devices, depending on the application, can operate with certain kind of fluids. Very common working fluids are gases and so far single gas flows in micro scale have been extensively studied [5][6][7][8][9][10][11][12]. However, only recently the focus has shifted to gas mixtures and the process of gas mixing that are frequently met in real applications [13][14][15][16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

A direct simulation Monte Carlo approach on the Riemann problem for gas mixtures

Meskos¹,

Stefanov²

2019

APPLICATION OF MATHEMATICS IN TECHNICAL AND NATURAL SCIENCES: 11th International Conference for Promoting the Application of Ma

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The Direct Simulation Monte Carlo method is employed to solve the "1D -Sod-Shock tube problem", a special case of Riemann problems, for gas mixtures. Initially, two different gas species are distributed separately in the high and low pressure sides of the tube without interacting with each other. For time greater than zero the species start mixing and shock and rarefaction waves are formed moving in opposite directions. In this work, the mixing process between different kinds of gas species was investigated by observing differences in waves' formation. The influence of the mass and diameter ratio between the species was studied in detail. It was found that greater mass differences had very strong effect on the mixing process, while the effects due to diameter differences were relatively small. Finally, it is shown that in case of single species the interaction molecular models of hard sphere, variable hard sphere and variable soft sphere gave the same results, while for gas mixtures the variable hard sphere and variable soft sphere models gave slightly different results.

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“…Tatsios et al [10] used the non-linear Shakhov kinetic model and the direct simulation Monte-Carlo (DSMC) model to simulate the fluid-flow in a square cavity. He found that both models gave close results in the investigated ranges.…”

Section: Introductionmentioning

confidence: 99%

“…Stefanov et al [14] investigated 3-D geometry with different aspect ratios Rayleigh-Benard flow problem, the investigation was for a set of different Froude and Knudsen numbers at a fixed temperature ratio. Although authors [10][11][12][13][14] investigated rarefied flow inside cavities, they did not investigate the heat transfer associated with natural convection inside the cavity. That is, their main investigation was focused on fluid-flow and the temperature distribution inside the cavity under different boundary conditions.…”

Section: Introductionmentioning

confidence: 99%

Rarefaction and scale effects on heat transfer characteristics for enclosed rectangular cavities heated from below

et al. 2019

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The fluid-flow and heat transfer in a buoyancy-driven microcavity heated from below are numerically investigated. In spite of the fact that microcavities are widely used in microelectro-mechanical systems, now a day, more interest in the evacuated cavity on Eqn. solar collectors are very common to reduce heat loss from the system. This paper provides a useful information for engineers to estimate heat transfer in low pressure cavities. The finite volume technique was used to solve the governing equations along with temperature jump and slip flow boundary conditions.The simulations are carried out for various cavity aspect ratios (H/L) and different Rayleigh number for both macroand micro-fluids. The effect of Knudsen number in the rarefied flow regime (microfluidic) has also been investigated. It is shown that for both cases the effect of aspect ratios on heat transfer becomes significant at high Rayleigh numbers and when the aspect ratio is below 5. It was also found that increasing Knudsen number reduces the heat transfer. The interaction between Nusselt, Rayleigh, Knudsen numbers, and the aspect ratio was investigated using the design of experiments, results show that no interaction between these parameters. To help engineers to estimate heat transfer in low pressure cavities, widely used in solar energy applications, a correlation for convection heat transfer coefficient is introduced.

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Nonequilibrium Gas Flow and Heat Transfer in a Heated Square Microcavity

Cited by 9 publications

References 24 publications

Predicting the Knudsen paradox in long capillaries by decomposing the flow into ballistic and collision parts

Predicting the Knudsen paradox in long capillaries by decomposing the flow into ballistic and collision parts

A direct simulation Monte Carlo approach on the Riemann problem for gas mixtures

Rarefaction and scale effects on heat transfer characteristics for enclosed rectangular cavities heated from below

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