Wall heat transfer effects on the hydro/thermal behaviour of Poiseuille flow in micro/nanochannels

Akhlaghi, Hassan; Roohi, Ehsan; Balaj, Mojtaba; Dadzie, S. Kokou

doi:10.1063/1.4894856

Cited by 15 publications

(6 citation statements)

References 31 publications

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“…Each cell is typically divided into subcells utilized to increase the accuracy of the selection of collision pairs. In the current work, the previous code of Akhlaghi and co-workers [11][12][13][14][15][16] is extended to simulate rarefied flow in the micro/nano channel geometry. The GHS collision model, introduced by Hassan and Hash [17], is utilized to consider accurate variation of the viscosity with the temperature over a wide range of temperature variations.…”

Section: Methodsmentioning

confidence: 99%

Effects of shear work on non-equilibrium heat transfer characteristics of rarefied gas flow through micro/nanochannels

Balaj¹,

Roohi²,

Akhlaghi³

2014

AIP Conference Proceedings

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In the current work, the effect of shear work due to the velocity slip on the non-equilibrium heat transfer in a pressure driven micro/nanochannel is evaluated under the constant wall heat flux boundary condition. As our simulation tool, the DSMC method is employed. Implementation of the wall heat flux in the DSMC method is performed using the ''modified Iterative'' technique. We investigate the effects of rarefaction, property variations and compressibility. The numerical results show that shear stress on the walls significantly affects all aspects of the flow behavior and heat transfer through micro/nanochannels such as heat flux rates. We also analyze the counter-gradient heat flow (cold to hot heat transfer) phenomenon appearing at the cooling conditions. It is observed that viscous dissipation affects the heat flux applied to the walls and may overcome the wall heat flux, i.e., in the case of low cooling wall heat flux condition, shear work may completely heat the flow field. Nusselt number singularity is also discussed.

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Section: Methodsmentioning

confidence: 99%

Effects of shear work on non-equilibrium heat transfer characteristics of rarefied gas flow through micro/nanochannels

Balaj¹,

Roohi²,

Akhlaghi³

2014

AIP Conference Proceedings

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“…Recently, the anti-Fourier (also known as cold-to-hot or counter-gradient) heat transfer phenomenon has been reported in rarefied gas flows 1 – 6 based on molecular simulations of gas flow using Direct Simulation Monte Carlo (DSMC) method. John et al .…”

Section: Introductionmentioning

confidence: 99%

“… 5 and Akhlaghi et al . 6 . It was observed that cold-to-hot heat transfer occurs at the terminal sections of the channel in the case of cooling walls.…”

Section: Introductionmentioning

confidence: 99%

Ballistic and Collisional Flow Contributions to Anti-Fourier Heat Transfer in Rarefied Cavity Flow

Akhlaghi

Roohi

Stefanov

2018

Sci Rep

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This paper investigates anti-Fourier heat transfer phenomenon in a rarefied gas confined within a lid-driven cavity using a novel flow decomposition technique in the direct simulation Monte Carlo (DSMC) method proposed by Stefanov and co-workers. An isothermal cavity with different degrees of flow rarefaction from near continuum to mid transition regimes was considered to investigate cold-to-hot heat transfer from ballistic/collision flow decomposition viewpoint. A new cold-to-hot heat transfer indicator in the form of a scalar product of normalized heat flow vector and normalized temperature gradient vector has been introduced for the overall, ballistic and collision parts of these vectors. Using the new indicator, contributions of ballistic and collision flow parts to temperature and heat flux components was investigated with a specific emphasis on the cold-to-hot heat transfer phenomenon. We demonstrated that both ballistic and collision flow parts contribute to the occurrence of cold-to-hot heat transfer. However, it was found out that considered separately both ballistic and collision parts of heat transfer, when related to corresponding ballistic and collision temperature fields, they are ever hot-to-cold for all degrees of flow rarefaction. Thus, cold-to-hot heat transfer is a result of a subtle interplay between ballistic and collision parts in the slip and transition Knudsen regimes.

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“…The authors previously examined the hydro/thermal behavior of rare¯ed gas°ow through micro/nanochannel. [13][14][15][16][17][18] Akhlaghi et al 13 proposed an \Iterative Technique" for applying a desired heat°ux distribution over the wall. It is shown that pressure distribution of microscale Poiseuille°ow may become less than the linear incompressible one for cooling condition.…”

Section: Introductionmentioning

confidence: 99%

“…Some qualitative observation on pressure and velocity changes due to wall heat transfer is captured in Ref. 17. However, the details of pressure, temperature and velocity¯elds of the Poiseuille°ow under gas-surface heat transfer are not covered in the past studies.…”

Section: Introductionmentioning

confidence: 99%

Rarefied gas flow behavior in micro/nanochannels under specified wall heat flux

Balaj

Akhlaghi

Roohi

2015

Int. J. Mod. Phys. C

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In this paper, we investigate the effects of convective heat transfer on the argon gas flow through micro/nanochannels subject to uniform wall heat flux (UWH) boundary condition using the direct simulation Monte Carlo (DSMC) method. Both the hot wall (q wall > 0) and the cold wall (q wall < 0) cases are considered. We consider the effect of wall heat flux on the centerline pressure, velocity profile and mass flow rate through the channel in the slip regime. The effects of rarefaction, property variations and compressibility are considered. We show that UWH boundary condition leads to the thermal transpiration. Our investigations showed that this thermal transpiration enhances the heat transfer rate at the walls in the case of hot walls and decreases it where the walls are being cooled. We also show that the deviation of the centerline pressure distribution from the linear distribution depends on the direction of the wall heat flux.

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Wall heat transfer effects on the hydro/thermal behaviour of Poiseuille flow in micro/nanochannels

Abstract: Articles you may be interested in A thorough study on thermal mass flux of rarefied flow through micro/nanochannels Appl.

Cited by 15 publications

References 31 publications

Effects of shear work on non-equilibrium heat transfer characteristics of rarefied gas flow through micro/nanochannels

Effects of shear work on non-equilibrium heat transfer characteristics of rarefied gas flow through micro/nanochannels

Ballistic and Collisional Flow Contributions to Anti-Fourier Heat Transfer in Rarefied Cavity Flow

Rarefied gas flow behavior in micro/nanochannels under specified wall heat flux

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