Simulation of a temperature drop for the flow of rarefied gases in microchannels

Gavasane, Abhimanyu; Agrawal, Amit; Pradeep, A. M.; Bhandarkar, Upendra

doi:10.1080/10407782.2017.1330091

Cited by 15 publications

(12 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Close to the channel outlet (x/L > 0.9), the gas temperature drops, which is attributed to the rapid gas expansion in that region, which is known as the expansion cooling phenomenon [20,65]. A similar behaviour close to the channel outlet has been reported by others [28,37,[43][44][45] for Poiseuille micro-flows in microchannels with uniform cross-sections. The overall heat flow direction for the problem considered in the present work is determined by both the thermal and pressure gradients in the microchannel [66].…”

Section: Resultssupporting

confidence: 72%

“…Despite the extensive interest in studying fluid flow at the micro-and nanoscales, numerical investigations of gas flow under nonequilibrium conditions are deficient in thermal analyses. Previous studies on thermal field analysis in microfluidics systems are mostly limited to the channels with uniform cross-sections (see, for instance, [37,[41][42][43][44][45][46][47][48]). Therefore, there is an indispensable need for detailed investigations on heat and fluid flow at the micro-and nanoscales under nonequilibrium conditions.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Pressure-Driven Nitrogen Flow in Divergent Microchannels with Isothermal Walls

2021

View full text Add to dashboard Cite

Gas flow and heat transfer in confined geometries at micro-and nanoscales differ considerably from those at macro-scales, mainly due to nonequilibrium effects such as velocity slip and temperature jump. Nonequilibrium effects increase with a decrease in the characteristic length-scale of the fluid flow or the gas density, leading to the failure of the standard Navier–Stokes–Fourier (NSF) equations in predicting thermal and fluid flow fields. The direct simulation Monte Carlo (DSMC) method is employed in the present work to investigate pressure-driven nitrogen flow in divergent microchannels with various divergence angles and isothermal walls. The thermal fields obtained from numerical simulations are analysed for different inlet-to-outlet pressure ratios (1.5≤Π≤2.5), tangential momentum accommodation coefficients, and Knudsen numbers (0.05≤Kn≤12.5), covering slip to free-molecular rarefaction regimes. The thermal field in the microchannel is predicted, heat-lines are visualised, and the physics of heat transfer in the microchannel is discussed. Due to the rarefaction effects, the direction of heat flow is largely opposite to that of the mass flow. However, the interplay between thermal and pressure gradients, which are affected by geometrical configurations of the microchannel and the applied boundary conditions, determines the net heat flow direction. Additionally, the occurrence of thermal separation and cold-to-hot heat transfer (also known as anti-Fourier heat transfer) in divergent microchannels is explained.

show abstract

Section: Resultssupporting

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Pressure-Driven Nitrogen Flow in Divergent Microchannels with Isothermal Walls

2021

View full text Add to dashboard Cite

show abstract

“…The centre-line pressure distribution is compared with the analytical solution of non-linear pressure distribution reported by Arkilic et al [20]. The present predictions are also compared with the DSMC data of compressible flow provided by Gavasane et al [25] on Argon gas for Kn = 0.124 at channel outlet, as illustrated in Fig. 2a.…”

Section: Validation Of Results With Analytical Solution and Dsmc Datamentioning

confidence: 76%

“…One of the middle Fig. 2 A comparison between variations of a centre-line pressure distribution along streamwise direction obtained in present simulation with analytical solution of Arkilic et al [20] and DSMC data of Gavasane et al [25], b centre-line velocities along streamwise direction, c centre-line static temperature distribution along streamwise direction, d slip velocity adjacent to the wall along streamwise direction, e cross-streamwise velocity profile obtained at half length of the channel, obtained in simulation, DSMC data [25], analytical solution of Karniadakis et al [26] for first and second-order slip boundary conditions ◂ Table 2 Validation of fRe for straight microchannel (α = 0.5) with analytical solution of Morini et al [27] The value in bold indicates the Kn value where minimum deviation is obtained with respect to the analytical solution Exit Kn (x/L = 1)…”

Section: Effect Of Reynolds Number On the Flow Characteristics Insidementioning

confidence: 74%

Influence of three-dimensional transverse micro-ridges on the Poiseuille number in a gaseous slip flow

Garg

Agrawal

2019

SN Appl. Sci.

Self Cite

View full text Add to dashboard Cite

Micro-ridges are regular micro-engineering structures protruding outward from the microchannel wall surface. The role of these micro-ridges in changing the friction factor (f) of a microchannel with internal rarefied gas flows is not explored in the literature. In this work, we present three-dimensional numerical simulations in a microchannel containing ridges arranged transverse to the flow direction. The length of the ridges is varied with respect to the pitch of the ridges; this ratio being christened as ridge fraction (δ). The effect of δ, ridge height ratio (h/H), Reynolds number (Re), Knudsen number (Kn) and Tangential momentum accommodation coefficient (α v) on the flow friction in terms of Poiseuille number (fRe) is investigated. In the continuum and slip regimes, it is found that fRe decreases with an increase in δ and h and a significant reduction in flow friction was shown with respect to a straight microchannel. There exists a critical height after which decrease in fRe does not occur. Further, fRe was observed to be a strong function of Re at high δ, which is attributed to the intensity of acceleration-deceleration experienced by the gas during the flow. Also, fRe is established to be directly proportional to α v. The various flow characteristics are scrutinised where vortices are found trapped inside the ridge affecting the dynamics of flow in the ridges, whose size increases on increasing the gas rarefaction. This comprehensive investigation of behaviour of slip flow in complex microchannels will be useful in designing micro-devices with reduced friction.

show abstract

“…Translational kinetic temperature The translational kinetic temperature is the unknown parameter to define the main parameters related to the thruster performance. During a gas expansion into a very low pressure environment there is a gas temperature drop [19][20][21]. Using the conservation of energy and the equipartition principle we can analyse the energy throughout the microchannel.…”

Section: Exhaust Velocitymentioning

confidence: 99%

An analytical model for characterizing the thrust performance of a Low-Pressure Micro-Resistojet

et al. 2018

View full text Add to dashboard Cite

There is a clear trend towards the developments of micro-propulsion system to enhance the capabilities of nanoand pico-satellites. A promising propulsion option to meet the strict requirements of these small satellites is the Low-Pressure Micro-Resistojet (LPM) which works under rarefied gas dynamic regime. To simplify the engineering design of this propulsion system an analytical model has been developed using the fundamental physical models. This analytical model is based on the Kinetic theory of gases and the Maxwell-Boltzmann distribution of molecular velocities to describe the macroscopic flow parameters such as mass flow rate, velocity and pressure, and then to estimate the thruster performance. The equations are well known, but they are applied in this case using a particular approach in order to describe the physics behind this micro-propulsion system. Comparisons between numerical simulations using the DSMC method and the results of the analytical model, as well as experimental results, have been carried out. The analytical model using an accurate estimation of the transmission coefficient compared to the numerical simulation presents a maximum difference of 3%.

show abstract

Simulation of a temperature drop for the flow of rarefied gases in microchannels

Cited by 15 publications

References 17 publications

Pressure-Driven Nitrogen Flow in Divergent Microchannels with Isothermal Walls

Pressure-Driven Nitrogen Flow in Divergent Microchannels with Isothermal Walls

Influence of three-dimensional transverse micro-ridges on the Poiseuille number in a gaseous slip flow

An analytical model for characterizing the thrust performance of a Low-Pressure Micro-Resistojet

Contact Info

Product

Resources

About