Numerical Modeling of Slip Flow and Heat Transfer Over Microcylinders With Lattice Boltzmann Method

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Zhenyu Liu ◽  
Zhiyu Mu ◽  
Huiying Wu
Keyword(s):  
Heat Transfer ◽  
Lattice Boltzmann ◽  
Gas Flow ◽  
Temperature Jump ◽  
Slip Flow ◽  
Velocity Slip ◽  
Curved Boundary ◽  
Slip Regime ◽  
Flow And Heat Transfer ◽  
Boltzmann Method

In this paper, a lattice Boltzmann (LB) model is established to simulate the gaseous fluid flow and heat transfer in the slip regime under the curved boundary condition. A novel curved boundary treatment is proposed for the LB modeling, which is a combination of the nonequilibrium extrapolation scheme for the curved boundary and the counter-extrapolation method for the macroscopic variables on the curved gas–solid interface. The established numerical model can accurately predict the velocity slip and temperature jump of the microscale gas flow on the curved surface, which agrees well with the analytical solution for the microcylindrical Couette flow and heat transfer. Then, the slip flow and the heat transfer over the single microcylinder are numerically studied in this work. It shows that the velocity slip and the temperature jump are obviously influenced by the Knudsen number and the Reynolds number, and the local Nusselt number depends on which gas rarefaction effect (velocity slip or temperature jump) is dominant. An increase in the Prandtl number leads to a decrease in the temperature jump, which enhances the heat transfer on the microcylinder surface. The numerical simulation of the flow and heat transfer over two microcylinders in tandem configuration are carried out to investigate the wake interference effect. The results show that the slip flow and heat transfer characteristics of the downstream microcylinder are influenced by the wake region behind the upstream cylinder as the spacing is small.

Slip Gas Flow and Heat Transfer in Confined Porous Media With Different Shape Cylinders

2021 ◽  
Author(s):  
Ammar Tariq ◽  
Zhenyu Liu
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Gas Flow ◽  
Velocity Slip ◽  
Heat Transfer Analysis ◽  
Variable Boundary ◽  
Flow And Heat Transfer ◽  
Multiple Relaxation Time ◽  
Permeability Increase ◽  
Boltzmann Method

Abstract With the recent advances in micro devices, an accurate gas flow and heat transfer analysis become more relevant considering the slip effect. A micro-scale, multiple-relaxation-time (MRT) lattice Boltzmann method with double distribution function approach is used to simulate flow and heat transfer through circular- and diamond-shaped cylinders at the porescale level. The velocity slip and temperature jump are captured at the boundaries using a non-equilibrium extrapolation scheme with the counter-extrapolation method. A pore-scale domain of micro-cylinders comprised of circle and diamond shape are studied. It is found that the permeability increases linearly with an increase in Knudsen number for both circular- and diamond-shaped cylinders. However, the permeability increase for circular obstacle is larger than that of the diamond one. A larger surface area for diamond cylinder will offer more resistance to flow, hence resulting in lower values. For heat transfer, the Nusselt number shows an increase with increasing Reynolds number, however, it decreases with the increase in porosity. Nusselt number values are found to be higher for a circular obstacle. A variable boundary gradient for circular obstacle could be a possible explanation for this difference.

Hydromagnetic flow and heat transfer with various nanoparticle additives past a wedge with high order velocity slip and temperature jump

2017 ◽  
Vol 95 (5) ◽  
pp. 440-449 ◽  
Author(s):  
Qianfang Liu ◽  
Jing Zhu ◽  
Bandar Bin-Mohsin ◽  
Liancun Zheng
Keyword(s):  
Heat Transfer ◽  
Temperature Jump ◽  
Slip Flow ◽  
Velocity Slip ◽  
Skin Friction Coefficient ◽  
High Order ◽  
Solid Particles ◽  
Flow And Heat Transfer ◽  
Homotopy Analysis ◽  
Fundamental Equations

Nanofluid slip flow with distinct solid particles past a wedge with convective surface and high order slip is discussed in this paper. The wedge model is modified by considering the effects of Brownian motion and thermophphoresis together with the high order velocity slip and temperature jump. In this study, the governing fundamental equations are first transformed into third-order ordinary differential equations and solved by using the homotopy analysis method (HAM). Through error analysis and comparison with previous research, the effectiveness of HAM is ascertained, and the crucial influence of nanoparticles and high-order slip on the fluid skin-friction coefficient and heat transfer coefficient is analyed. Thermophphoresis parameter and suction/injection parameter are found to cause an increase in velocity and temperature. The rate of heat transfer in the Cu–water nanofluid is found to be higher than the others.

LATTICE BOLTZMANN METHOD IN SIMULATION OF THERMAL MICRO-FLOW WITH TEMPERATURE JUMP

2006 ◽  
Vol 17 (05) ◽  
pp. 603-614 ◽  
Author(s):  
ZHI-WEI TIAN ◽  
CHUN ZOU ◽  
ZHAO-HUI LIU ◽  
ZHAO-LI GUO ◽  
HONG-JUAN LIU ◽  
...  
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Gas Flow ◽  
Heat Dissipation ◽  
Temperature Jump ◽  
Velocity Slip ◽  
Boundary Treatment ◽  
Boundary Velocity ◽  
Micro Flow ◽  
Boltzmann Method

We simulate the gas flow and heat transfer in micro-Couette flow by the lattice Boltzmann method (LBM). A new boundary treatment is adopted in the numerical experiment in order to capture the velocity slip and the temperature jump of the wall boundary. Velocity and temperature profiles are in good agreement with the analytic results, which exhibits the availability of this model and boundary treatment in describing thermal micro-flow with viscous heat dissipation. We also find the upper boundary's temperature jump is zero at the critical Ec, which is around 3.0 with different Kn.

Modeling of Heat Transfer in Microchannel Gas Flow

2010 ◽  
Vol 133 (2) ◽  
Author(s):  
Tomasz Lewandowski ◽  
Tomasz Ochrymiuk ◽  
Justyna Czerwinska
Keyword(s):  
Heat Transfer ◽  
Gas Flow ◽  
Temperature Jump ◽  
Flow Behavior ◽  
Slip Flow ◽  
Velocity Slip ◽  
Gas Temperature ◽  
Viscous Effects ◽  
Strongly Connected ◽  
The One

Due to the existence of a velocity slip and temperature jump on the solid walls, the heat transfer in microchannels significantly differs from the one in the macroscale. In our research, we have focused on the pressure driven gas flows in a simple finite microchannel geometry, with an entrance and an outlet, for low Reynolds (Re<200) and low Knudsen (Kn<0.01) numbers. For such a regime, the slip induced phenomena are strongly connected with the viscous effects. As a result, heat transfer is also significantly altered. For the optimization of flow conditions, we have investigated various temperature gradient configurations, additionally changing Reynolds and Knudsen numbers. The entrance effects, slip flow, and temperature jump lead to complex relations between flow behavior and heat transfer. We have shown that slip effects are generally insignificant for flow behavior. However, two configuration setups (hot wall cold gas and cold wall hot gas) are affected by slip in distinguishably different ways. For the first one, which concerns turbomachinery, the mass flow rate can increase by about 1% in relation to the no-slip case, depending on the wall-gas temperature difference. Heat transfer is more significantly altered. The Nusselt number between slip and no-slip cases at the outlet of the microchannel is increased by about 10%.

Nusselt Number Prediction for Slip Flow in Confined Porous Media Based on Lattice Boltzmann Method

2019 ◽  
Author(s):  
Ammar Tariq ◽  
Zhenyu Liu ◽  
Zhiyu Mu ◽  
Huiying Wu
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Nusselt Number ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Slip Flow ◽  
Flow And Heat Transfer ◽  
Prime Concern ◽  
Multiple Relaxation Time ◽  
Boltzmann Method

Abstract Understanding flow and heat transfer in porous media is a matter of prime concern for micro devices. In this work, slip flow and heat transfer of gaseous fluid through the confined porous media is numerically simulated using a multiple-relaxation-time lattice Boltzmann method. The method is employed using an effective curved boundary treatment based on non-equilibrium extrapolation and counter-extrapolation methods. Nusselt number prediction for varying porosity, Knudsen and Reynolds number are studied. Based on the obtained numerical results, it is proved that the current technique can be used to effectively model slip flow and heat transfer at pore-scale.

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