Comprehensive Evaluation of a New Type of Smoluchowski Temperature Jump Condition

AIAA Journal ◽  
2018 ◽  
Vol 56 (11) ◽  
pp. 4621-4625 ◽  
Author(s):  
Ashwani Assam ◽  
Nikhil Kalkote ◽  
Nishanth Dongari ◽  
Vinayak Eswaran
Keyword(s):  
Temperature Jump ◽  
Comprehensive Evaluation ◽  
Jump Condition ◽  
New Type

New Type of Smoluchowski Temperature Jump Condition Considering the Viscous Heat Generation

AIAA Journal ◽  
2017 ◽  
Vol 55 (2) ◽  
pp. 474-483 ◽  
Author(s):  
Nam T. P. Le ◽  
Ngoc Anh Vu ◽  
Le Tan Loc
Keyword(s):  
Heat Generation ◽  
Temperature Jump ◽  
Jump Condition ◽  
Viscous Heat ◽  
New Type

On Temperature Jump Condition for Slip Flow in a Microchannel With Constant Wall Temperature

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Yutaka Asako ◽  
Chungpyo Hong
Keyword(s):  
Boundary Condition ◽  
Viscous Dissipation ◽  
Wall Temperature ◽  
Energy Equation ◽  
Temperature Jump ◽  
Slip Flow ◽  
Jump Condition ◽  
Constant Wall Temperature ◽  
Maximum Heat ◽  
Maximum Heat Transfer

The analytical solution in the fully developed region of a slip flow in a circular microtube with constant wall temperature is obtained to verify the conventional temperature jump boundary condition when both viscous dissipation (VD) and substantial derivative of pressure (SDP) terms are included in the energy equation. Although the shear work term is not included in the conventional temperature jump boundary condition explicitly, it is verified that the conventional temperature jump boundary condition is valid for a slip flow in a microchannel with constant wall temperature when both viscous dissipation and substantial derivative of pressure terms are included in the energy equation. Numerical results are also obtained for a slip flow in a developing region of a circular tube. The results showed that the maximum heat transfer rate decreases with increasing Mach number.

Investigation of non-equilibrium boundary conditions considering sliding friction for micro/nano flows

2019 ◽  
Vol 29 (8) ◽  
pp. 2501-2523
Author(s):  
Ashwani Assam ◽  
Nikhil Kalkote ◽  
Nishanth Dongari ◽  
Vinayak Eswaran
Keyword(s):  
Slip Velocity ◽  
Sliding Friction ◽  
Temperature Jump ◽  
Jump Condition ◽  
Surface Flow ◽  
Pressure Jump ◽  
Gas Flows ◽  
Flow Properties ◽  
Content Type ◽  
Pressure Driven Flow

Purpose Accurate prediction of temperature and heat is crucial for the design of various nano/micro devices in engineering. Recently, investigation has been carried out for calculating the heat flux of gas flow using the concept of sliding friction because of the slip velocity at the surface. The purpose of this study is to exetend the concept of sliding friction for various types of nano/micro flows. Design/methodology/approach A new type of Smoluchowski temperature jump considering the viscous heat generation (sliding friction) has recently been proposed (Le and Vu, 2016b) as an alternative jump condition for the prediction of the surface gas temperature at solid interfaces for high-speed non-equilibrium gas flows. This paper investigated the proposed jump condition for the nano/microflows which has not been done earlier using four cases: 90° bend microchannel pressure-driven flow, nanochannel backward facing step with a pressure-driven flow, nanoscale flat plate and NACA 0012 micro-airfoil. The results are compared with the available direct simulation Monte Carlo results. Also, this paper has demonstrated low-speed preconditioned density-based algorithm for the rarefied gas flows. The algorithm captured even very low Mach numbers of 2.12 × 10−5. Findings Based on this study, this paper concludes that the effect of inclusion of sliding friction in improving the thermodynamic prediction is case-dependent. It is shown that its performance depends not only on the slip velocity at the surface but also on the mean free path of the gas molecule and the shear stress at the surface. A pressure jump condition was used along with the new temperature jump condition and it has been found to often improve the prediction of surface flow properties significantly. Originality/value This paper extends the concept of using sliding friction at the wall for micro/nano flows. The pressure jump condition was used which has been generally ignored by researchers and has been found to often improve the prediction of surface flow properties. Different flow properties have been studied at the wall apart from only temperature and heat flux, which was not done earlier.

A new type of boundary layer in a rapidly rotating gas

1983 ◽  
Vol 126 ◽  
pp. 431-442 ◽  
Author(s):  
Takuya Matsuda ◽  
Keizo Nakagawa
Keyword(s):  
Boundary Layer ◽  
Temperature Jump ◽  
Ekman Layer ◽  
Infinite Length ◽  
Gaseous Flow ◽  
Ekman Number ◽  
New Type ◽  
Vertical Walls ◽  
Source Sink

Gaseous flow in a pie-shaped cylinder of infinite length rotating about the apex is considered. The horizontal flow is induced either by the temperature distribution or by the source/sink distribution on the walls θ = constant. It is found that along the vertical walls θ = constant the E½ boundary layer is formed, where E is the Ekman number. Although the equation governing the above boundary layer is very similar to that of the Ekman layer, it is a new type of boundary layer which may be called the buoyancy layer. Along the wall on which r is constant thermal boundary layers very similar to the Stewartson layers are found to be formed. The role of these layers is to mediate the temperature jump. These layers disappear in the incompressible limit.

scholarly journals New temperature jump boundary condition in high-speed rarefied gas flow simulations

2017 ◽  
Vol 39 (2) ◽  
pp. 165-176
Author(s):  
Nam Tuan Phuong Le ◽  
Ngoc Anh Vu ◽  
Le Tan Loc ◽  
Tran Ngoc Thoai
Keyword(s):  
High Speed ◽  
Gas Flow ◽  
Sliding Friction ◽  
Temperature Jump ◽  
Stokes Equations ◽  
Rarefied Gas ◽  
Jump Condition ◽  
Rarefied Gas Flow ◽  
Flow Simulations ◽  
Knudsen Numbers

The effect of the sliding friction has been important in calculating the heat flux of gas flow from the surface since there is some slip over the surface. There has not been any the temperature jump condition including the sliding friction part so far. In this paper, we will propose a new temperature jump condition that includes the sliding friction. Our new temperature jump condition will be evaluated for NACA0012 micro-airfoil in high-speed rarefied gas flow simulations using the CFD method, which solves the Navier-Stokes equations within the OpenFOAM framework with working gas as air. The airfoil case is simulated with various Knudsen numbers from 0.026 to 0.26, and the angles-of-attack (AOAs) from 0-deg to 20-deg. The surface gas temperatures predicting by our new temperature jump condition give good agreements with the DSMC data, especially the NACA0012 micro-airfoil cases with the high Knudsen numbers, Kn = 0.1, and Kn = 0.26 with AOA = 20-deg. for the lower surface.

Two-phase model for mixed convection and flow enhancement of a nanofluid in an inclined channel patterned with heated slip stripes

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Subhasree Dutta ◽  
Somnath Bhattacharyya ◽  
Ioan Pop
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Temperature Jump ◽  
Volume Fraction ◽  
Volume Flow Rate ◽  
Homogeneous Model ◽  
Jump Condition ◽  
Two Phase ◽  
Content Type ◽  
The Impact

Purpose The purpose of this study is to analyze the heat transfer and flow enhancement of an Al2O3-water nanofluid filling an inclined channel whose lower wall is embedded with periodically placed discrete hydrophobic heat sources. Formation of a thin depletion layer of low viscosity over each hydrophobic heated patch leads to the velocity slip and temperature jump condition at the interface of the hydrophobic patch. Design/methodology/approach The mixed convection of the nanofluid is analysed based on the two-phase non-homogeneous model. The governing equations are solved numerically through a control volume approach. A periodic boundary condition is adopted along the longitudinal direction of the modulated channel. A velocity slip and temperature jump condition are imposed along with the hydrophobic heated stripes. The paper has validated the present non-homogeneous model with existing experimental and numerical results for particular cases. The impact of temperature jump condition and slip velocity on the flow and thermal field of the nanofluid in mixed convection is analysed for a wide range of governing parameters, namely, Reynolds number (50 ≤ Re ≤ 150), Grashof number ( 103≤Gr≤5×104), nanoparticle bulk volume fraction ( 0.01≤φb≤0.05), nanoparticle diameter ( 30≤dp≤60) and the angle of inclination ( −60°≤σ≤60°). Findings The presence of the thin depletion layer above the heated stripes reduces the heat transfer and augments the volume flow rate. Consideration of the nanofluid as a coolant enhances the rate of heat transfer, as well as the entropy generation and friction factor compared to the clear fluid. However, the rate of increment in heat transfer suppresses by a significant margin of the loss due to enhanced entropy generation and friction factor. Heat transfer performance of the channel diminishes as the channel inclination angle with the horizontal is increased. The paper has also compared the non-homogeneous model with the corresponding homogeneous model. In the non-homogeneous formulation, the nanoparticle distribution is directly affected by the slip conditions by virtue of the no-normal flux of nanoparticles on the slip planes. For this, the slip stripes augment the impact of nanoparticle volume fraction compared to the no-slip case. Originality/value This paper finds that the periodically arranged hydrophobic heat sources on the lower wall of the channel create a significant augmentation in the volume flow rate, which may be crucial to augment the transport process in mini- or micro-channels. This type of configuration has not been addressed in the existing literature.

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