Magnetic nanofluid flow and convective heat transfer in a porous cavity considering Brownian motion effects

2018 ◽  
Vol 30 (1) ◽  
pp. 012003 ◽  
Author(s):  
M. Sheikholeslami ◽  
Houman B. Rokni
Keyword(s):  
Heat Transfer ◽  
Brownian Motion ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Nanofluid Flow ◽  
Magnetic Nanofluid ◽  
Porous Cavity

Numerical investigation of nanofluid particle migration and convective heat transfer in microchannels using an Eulerian–Lagrangian approach

2019 ◽  
Vol 878 ◽  
pp. 62-97 ◽  
Author(s):  
Omar Z. Sharaf ◽  
Ashraf N. Al-Khateeb ◽  
Dimitrios C. Kyritsis ◽  
Eiyad Abu-Nada
Keyword(s):  
Heat Transfer ◽  
Brownian Motion ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Particle Distribution ◽  
Reynolds Numbers ◽  
Streamwise Direction ◽  
Nanofluid Flow ◽  
Low Reynolds Numbers ◽  
Low Reynolds

An Eulerian–Lagrangian modelling approach was employed in order to investigate the flow field, heat transfer and particle distribution in nanofluid flow in a parallel-plate microchannel, with a focus on relatively low Reynolds numbers ($Re\leqslant 100$). Momentum and thermal interactions between fluid and particle phases were accounted for using a transient two-way coupling algorithm implemented within an in-house code that tracked the simultaneous evolution of the carrier and particulate phases while considering timescale differences between the two phases. The inaccuracy of assuming a homogeneous particle distribution in modelling nanofluid flow in microchannels was established. In particular, shear rate and thermophoresis were found to play a key role in the lateral migration of nanoparticles and in the formation of particle depletion and accumulation regions in the vicinity of the channel walls. At low Reynolds numbers, nanoparticle distribution near the walls was observed to gradually flatten in the streamwise direction. On the other hand, for relatively higher Reynolds numbers, higher particle non-uniformities were observed in the vicinity of the channel walls. Furthermore, it was established that convective heat transfer between channel walls and the bulk fluid can either improve or deteriorate with the addition of nanoparticles, depending on whether the flow exceeded a critical Reynolds number of enhancement. It was also established that Brownian motion and thermophoresis had a major role in nanoparticle deposition on the channel walls. In particular, Brownian motion was the main deposition mechanism for nano-sized particles, whereas due to thermophoresis, nanoparticles were repelled away from channel walls. The result of the competition between the two is that deposition gradually increased along the streamwise direction.

Assessment of Single and Two-Phase Models for Nanofluid Flow at the Entrance Region of a Uniformly Heated Tube

2012 ◽  
Author(s):  
Sinan Goktepe ◽  
Kunt Atalik ◽  
Hakan Erturk
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Friction Factor ◽  
Convective Heat ◽  
Control Volume ◽  
Convective Heat Transfer Coefficient ◽  
Computational Cost ◽  
Nanofluid Flow ◽  
Two Phase ◽  
Phase Models

Hydrodynamic and thermal characteristics of Al2O3 – water nanofluid flow at entry region of a uniformly heated pipe are studied applying finite control volume method (FCV). Single phase and Eulerian-Eulerian two-phase models were used in modelling of nanofluid flow and heat transfer. The two methods are evaluated by comparing predicted convective heat transfer coefficients and friction factor with experimental results from literature. Solutions with two different velocity pressure coupling algorithms, Full Multiphase Coupled, and Phase Coupled Semi-Implicit Method for Pressure Linked Equations are also compared in terms of accuracy and computational cost. Two-phase model predicts convective heat transfer coefficient and friction factor more accurately at the entry region. Moreover, computational cost can be reduced by implementing Full Multiphase Coupled scheme.

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