Mohamed Shaimi^* , Rabha Khatyr, Jaafar Khalid Naciri

Frontiers in Heat and Mass Transfer, Vol.20, pp. 1-14, 2023, DOI:10.5098/hmt.20.23

Abstract This paper presents an exact analytical solution to the extended Graetz problem in microchannels and microtubes, including axial heat conduction, viscous dissipation, and rarefaction effects for an imposed constant wall temperature. The flow in the microchannel or microtube is assumed to be hydrodynamically fully developed. At the same time, the first-order slip-velocity and temperature jump models represent the wall boundary conditions. The energy equation is solved analytically, and the solution is obtained in terms of Kummer functions with expansion constants directly determined from explicit expressions. The local and fully developed Nusselt numbers are calculated in terms of the Péclet number,… More >

Ningbo Guo, Xianming Gao^*, Duanling Li, Jixing Zhang, Penghui Yin, Mengyi Hua

CMES-Computer Modeling in Engineering & Sciences, Vol.136, No.3, pp. 3061-3082, 2023, DOI:10.32604/cmes.2023.026657

Abstract Computational fluid dynamics was used and a numerical simulation analysis of boiling heat transfer in microchannels with three depths and three cross-sectional profiles was conducted. The heat transfer coefficient and bubble generation process of three microchannel structures with a width of 80 μm and a depth of 40, 60, and 80 μm were compared during the boiling process, and the factors influencing bubble generation were studied. A visual test bench was built, and test substrates of different sizes were prepared using a micro-nano laser. During the test, the behavior characteristics of the bubbles on the boiling surface and the temperature… More >

Mehdi Moslemi¹, Motahare Mahmoodnezhad¹, S. A. Edalatpanah^1,*, Sulima Ahmed Mohammed Zubair², Hamiden Abd El-Wahed Khalifa^2,3

CMES-Computer Modeling in Engineering & Sciences, Vol.134, No.3, pp. 1957-1973, 2023, DOI:10.32604/cmes.2022.021481

Abstract In this research, a numerical study of mixed convection of non-Newtonian fluid and magnetic field effect along a vertical wavy surface was investigated. A simple coordinate transformation to transform wavy surface to a flat surface is employed. A cubic spline collocation numerical method is employed to analyze transformed equations. The effect of various parameters such as Reynolds number, volume fraction 0-, Hartmann number, and amplitude of wave length was evaluated in improving the performance of a wavy microchannel. According to the presented results, the sinusoidal shape of the microchannel has a direct impact on heat transfer. By increasing the microchannel… More >

Jie-Chao Chen, Rui-Hao Luo, Wu-Zhi Yuan, Nan-Long Hong^*, Wen-Hao Wang

Energy Engineering, Vol.119, No.4, pp. 1327-1339, 2022, DOI:10.32604/ee.2022.019331

Abstract For effective water-based thermal management of high heat generating CPU chip, a series of numerical simulation has been conducted to study the effects of heat flux, fin height and flow rate on convective thermal performance of the plate-fin microchannel heat sinks. The characteristics of heat transfer and flow resistance have been quantificationally discussed and JF factor is employed to evaluate the comprehensive efficiency of convective heat transfer of microchannel heat sink. Results show that the increase in fin height and flow rate of cooling water is helpful to decrease the maximum temperature of CPU chip. Large flow rate and heat… More >

Xiaokang Tian¹, Kai Yue^1,2,*, Yu You^1,2, Yongjian Niu¹, Xinxin Zhang^1,2

FDMP-Fluid Dynamics & Materials Processing, Vol.17, No.2, pp. 301-317, 2021, DOI:10.32604/fdmp.2021.013521

Abstract The heat transfer performances of a microchannel heat sink in the presence of a nanofluid can be affected by the attachment of nanoparticle (NP) on the microchannel wall. In this study, the mechanisms underlying NP transport and attachment are comprehensively analyzed by means of a coupled double-distribution-function lattice Boltzmann model combined with lattice-gas automata. Using this approach, the temperature distribution and the two-phase flow pattern are obtained for different values of the influential parameters. The results indicate that the number of attached NPs decrease exponentially as their diameter and the fluid velocity grow. An increase in the wall temperature leads… More >

A. Aissa^{1, *}, M. E. A. Slimani², F. Mebarek-Oudina³, R. Fares¹, A. Zaim¹, L. Kolsi^{4, 5}, M. Sahnoun¹, M. E. Ganaoui⁶

FDMP-Fluid Dynamics & Materials Processing, Vol.16, No.2, pp. 147-159, 2020, DOI:10.32604/fdmp.2020.04073

Abstract In this paper, flow of slightly rarefied compressible nitrogen in microchannels has been investigated numerically for low values of Reynolds and Mach numbers. The 2D governing equations were solved using Finite Element Method with first-order slip boundary conditions (Comsol Multiphysics software). A validation was performed by comparing with similar configuration from the literature. It was found that our model can accurately predict the pressure driven flow in microchannels. Several interesting findings are reported about the Relative pressure, longitudinal velocity, Mach number, effect of gas rarefaction and flow rate. More >

Tawfiq Chekifi^1,*

FDMP-Fluid Dynamics & Materials Processing, Vol.15, No.5, pp. 545-555, 2019, DOI:10.32604/fdmp.2019.01793

Abstract Numerical simulation using Ansys Fluent code is performed, to investigate droplet generation in cross-junction based VOF method. Droplets of water are generated by the shear stress applied by continuous phase (oil), two configurations of cross-junction are suggested; the first is a simple model no modification is performed at the outer channel, while the second model is characterized by a lateral obstacle. we study the effect of velocity ratio, viscous parameter, interfacial tension, flow condition on droplet size and frequency, the effect of lateral obstacles on droplets generation is also focused and analysed. The numerical simulations showed that the velocity ratio… More >

Zhen Wang¹, Yi Sui¹, Wen Wang¹, Dominique Barthѐs-Biesel², Anne-Virginie Salsac^2,*

Molecular & Cellular Biomechanics, Vol.16, Suppl.2, pp. 42-43, 2019, DOI:10.32604/mcb.2019.07148

Abstract Capsules are liquid droplets enclosed by a thin membrane which can resist shear deformation. They are widely found in nature (e.g. red blood cells) and in numerous applications (e.g. food, cosmetic, biomedical and pharmaceutical industries [1]), where they often flow through a complicated network of tubes or channels: this is the case for RBCs in the human circulation or for artificial capsules flowing through microfluidic devices. Central to these flows is the dynamic motion of capsules at bifurcations, in particular the question of path selection. A good understanding of this problem is indeed needed to elucidate some intriguing phenomena in… More >

Xinyu You¹, Jionghui Liu¹, Nan Hua^1,3, Ji Wang⁵, Rongji Xu^1,4, Guangxu Yu², Huasheng Wang^1,*

The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.3, pp. 143-143, 2019, DOI:10.32604/icces.2019.04732

Abstract The paper reports preliminary measurement results for flow boiling heat transfer of refrigerant R1233zd in parallel horizontal microchannels. The aluminum test section consists of two blocks and has 10 parallel channels with 1.0 mm in width, 1.5 mm in height and 440 mm in length. Five small thermocouple holes with diameter 0.6 mm and depth 20 mm were drilled at 10 locations along the channel on the two aluminum blocks, respectively. Local heat flux and channel surface temperature along the channel were obtained using the inverse heat conduction method [1] based on temperatures accurately measured by 100 thermocouples. Local saturation… More >

J.H. Horng¹, C.C. Wei¹, Y.L. Ye², C.H. Huang¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.15, No.1, pp. 9-18, 2010, DOI:10.3970/icces.2010.015.009

Abstract In this paper, four kinds of biocompatible SAMs are used to improve adhesion property and fluorescence reaction property on specimen surfaces. The result of experiment shows that OTS film demonstrates contact angles are all larger than 100 degrees in different immersing time and it reveal the best hydrophobic property after 24 hours. The declination angle experiment demonstrates that the OTS film has best flowing property and same trend of friction coefficient; it indicates that the declination angle experiment can reveal the degree of microchannel adhesion property better than contact angle experiment. It can be found that the OTS film can… More >