scholarly journals Temperature jump and slip velocity calculations from an anisotropic scattering kernel

2005 ◽  
Vol 358 (2-4) ◽  
pp. 328-346 ◽  
Author(s):  
S. Kokou Dadzie ◽  
J. Gilbert Méolans
Keyword(s):  
Slip Velocity ◽  
Temperature Jump ◽  
Anisotropic Scattering ◽  
Scattering Kernel

Magnetic field effects on the slip velocity and temperature jump of nanofluid forced convection in a microchannel

2015 ◽  
Vol 230 (11) ◽  
pp. 1921-1936 ◽  
Author(s):  
Arash Karimipour ◽  
Masoud Afrand
Keyword(s):  
Magnetic Field ◽  
Forced Convection ◽  
Slip Velocity ◽  
Temperature Jump ◽  
Stokes Equations ◽  
Volume Fraction ◽  
Computer Code ◽  
Navier Stokes ◽  
Magnetic Field Effects ◽  
Navier Stokes Equations

Forced convection of water–Cu nanofluid in a two-dimensional microchannel is studied numerically. The microchannel wall is divided into three parts. The entry and exit ones are kept insulated while the middle one has more temperature than the inlet fluid. The whole of microchannel is under the influence of a magnetic field with uniform strength of B0. Slip velocity and temperature jump are involved along the microchannel walls for different values of slip coefficient such as B = 0.001, B = 0.01, and B = 0.1 for Re = 10, Re = 50, and Re = 100. Navier–Stokes equations are discretized and numerically solved by a developed computer code in FORTRAN. Results are presented as the velocity, temperature, and Nusselt number profiles. Moreover, the effect of magnetic field on slip velocity and temperature jump is investigated for the first time in the present work. Larger Hartmann number, Reynolds number, and volume fraction correspond to more heat transfer rate; however, the effects of Ha and ϕ are more significant at higher Re.

Heat Transfer Through a Gas Between Parallel Plates

1977 ◽  
Vol 32 (9) ◽  
pp. 914-926 ◽  
Author(s):  
L. Waldmann
Keyword(s):  
Heat Transfer ◽  
Particle Distribution ◽  
Temperature Jump ◽  
Exact Formula ◽  
Parallel Plates ◽  
Total Heat Transfer ◽  
Linearized Boltzmann Equation ◽  
Scattering Kernel ◽  
Interfacial Scattering ◽  
Transport Relaxation

Within the framework of boundary conditions recently developed for the linearized Boltzmann equation 1 the problem of heat transfer between parallel plates can be solved in terms of "transport- relaxation eigenfunctions". The particle distribution function and the total heat transfer in the Knudsen case are exactly expressed by integrals over the interfacial scattering kernel occurring in the new scheme. A detailed discussion of the general case gives an exact formula and sign statement for the temperature jump at parallel plates. An approximation, which encompasses v. Smoluchowski's approach, lies at hand. This approximation is also readily confirmed by a moment method.

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.

Determining the Optimum Arrangement of Micromixers in a Microchannel Filled with CuO-Water Nanofluid via Minimizing Entropy Generation

2017 ◽  
Vol 378 ◽  
pp. 39-58 ◽  
Author(s):  
Ahmad Ababaei ◽  
Mahmoud Abbaszadeh ◽  
Ali Akbar Abbasian Arani
Keyword(s):  
Boundary Conditions ◽  
Parallel Plate ◽  
Slip Velocity ◽  
Temperature Jump ◽  
Volume Fraction ◽  
Reynolds Numbers ◽  
Governing Equations ◽  
Simpler Algorithm ◽  
Optimum Arrangement ◽  
Volume Method

In this study, the flow of CuO-water nanofluid in a parallel-plate microchannel in the presence of several micromixers is examined to find optimum arrangements of the micromixers. The governing equations, which are accompanied with the slip velocity and temperature jump boundary conditions, are solved by the Finite Volume Method and SIMPLER algorithm. The study is conducted for the Reynolds numbers in the range of 10 ≤ Re ≤ 100, Knudsen numbers ranging of 0 ≤ Kn ≤ 0.1 and volume fraction of nanoparticles ranging of 0 ≤ ϕ ≤ 4%. The results show that the optimum arrangements of the micromixers belong to cases in which the heights of micromixers are smaller, the distance between them is lower, and their numbers are more.

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