Natural convection flows of carbon nanotubes nanofluids with Prabhakar‐like thermal transport

2020 ◽  
Author(s):  
Thanaa Elnaqeeb ◽  
Nehad Ali Shah ◽  
Itrat Abbas Mirza
Keyword(s):  
Carbon Nanotubes ◽  
Natural Convection ◽  
Thermal Transport

scholarly journals A Thermal Transport Study of Branched Carbon Nanotubes with Cross and T-Junctions

2021 ◽  
Vol 11 (13) ◽  
pp. 5933
Author(s):  
Wei-Jen Chen ◽  
I-Ling Chang
Keyword(s):  
Heat Transfer ◽  
Carbon Nanotubes ◽  
Thermal Management ◽  
Thermal Transport ◽  
Topological Defects ◽  
Branch Length ◽  
Phonon Transport ◽  
Heat Current ◽  
Transport Mechanisms ◽  
Non Equilibrium Molecular Dynamics

This study investigated the thermal transport behaviors of branched carbon nanotubes (CNTs) with cross and T-junctions through non-equilibrium molecular dynamics (NEMD) simulations. A hot region was created at the end of one branch, whereas cold regions were created at the ends of all other branches. The effects on thermal flow due to branch length, topological defects at junctions, and temperature were studied. The NEMD simulations at room temperature indicated that heat transfer tended to move sideways rather than straight in branched CNTs with cross-junctions, despite all branches being identical in chirality and length. However, straight heat transfer was preferred in branched CNTs with T-junctions, irrespective of the atomic configuration of the junction. As branches became longer, the heat current inside approached the values obtained through conventional prediction based on diffusive thermal transport. Moreover, directional thermal transport behaviors became prominent at a low temperature (50 K), which implied that ballistic phonon transport contributed greatly to directional thermal transport. Finally, the collective atomic velocity cross-correlation spectra between branches were used to analyze phonon transport mechanisms for different junctions. Our findings deeply elucidate the thermal transport mechanisms of branched CNTs, which aid in thermal management applications.

The effects of diameter and chirality on the thermal transport in free-standing and supported carbon-nanotubes

2012 ◽  
Vol 100 (23) ◽  
pp. 233105 ◽  
Author(s):  
Bo Qiu ◽  
Yan Wang ◽  
Qing Zhao ◽  
Xiulin Ruan
Keyword(s):  
Carbon Nanotubes ◽  
Thermal Transport ◽  
Free Standing

scholarly journals Natural convection of Bingham fluids in rectangular cross-sectional cylindrical annuli with differentially heated vertical walls

2019 ◽  
Vol 29 (1) ◽  
pp. 43-77 ◽  
Author(s):  
Sahin Yigit ◽  
Nilanjan Chakraborty
Keyword(s):  
Boundary Condition ◽  
Nusselt Number ◽  
Natural Convection ◽  
Yield Stress ◽  
Thermal Transport ◽  
Second Order ◽  
Bingham Fluids ◽  
Cross Sectional ◽  
Content Type ◽  
The Mean

PurposeThis paper aims to numerically analyse natural convection of yield stress fluids in rectangular cross-sectional cylindrical annular enclosures. The laminar steady-state simulations have been conducted for a range of different values of normalised internal radius (ri/L1/8 to 16, whereLis the difference between outer and inner radii); aspect ratio (AR=H/Lfrom 1/8 to 8 whereHis the enclosure height); and nominal Rayleigh number (Rafrom 103to 106) for a single representative value of Prandtl number (Pris 500).Design/methodology/approachThe Bingham model has been used to mimic the yield stress fluid motion, and numerical simulations have been conducted for both constant wall temperature (CWT) and constant wall heat flux (CWHF) boundary conditions for the vertical side walls. The conservation equations of mass, momentum and energy have been solved in a coupled manner using the finite volume method where a second-order central differencing scheme is used for the diffusive terms and a second-order up-wind scheme is used for the convective terms. The well-known semi-implicit method for pressure-linked equations algorithm is used for the coupling of the pressure and velocity.FindingsIt is found that the mean Nusselt number based on the inner peripheryNu¯iincreases (decreases) with an increase inRa(Bn) due to augmented buoyancy (viscous) forces irrespective of the boundary condition. The ratio of convective to diffusive thermal transport increases with increasingri/Lfor both Newtonian (i.e.Bn= 0) and Bingham fluids regardless of the boundary condition. Moreover, the mean Nusselt numberNu¯inormalised by the corresponding Nusselt number due to pure conductive transport (i.e.Nu¯i/(Nu¯i)cond) shows a non-monotonic trend with increasingARin the CWT configuration for a given set of values ofRa,Pr,Lifor both Newtonian (i.e.Bn= 0) and Bingham fluids, whereasNu¯i/(Nu¯i)condincreases monotonically with increasingARin the CWHF configuration. The influences of convective thermal transport strengthen while thermal diffusive transport weakens with increasingAR, and these competing effects are responsible for the non-monotonicNu¯i/(Nu¯i)condvariation withARin the CWT configuration.Originality/valueDetailed scaling analysis is utilised to explain the observed influences ofRa,BN,ri/LandAR, which along with the simulation data has been used to propose correlations forNu¯i.

Thermal transport of oil and polymer composites filled with carbon nanotubes

2011 ◽  
Vol 105 (4) ◽  
pp. 781-788 ◽  
Author(s):  
Vitaliy Datsyuk ◽  
Milana Lisunova ◽  
Maria Kasimir ◽  
Svitlana Trotsenko ◽  
Kati Gharagozloo-Hubmann ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Polymer Composites ◽  
Thermal Transport

Thermal Transport During Nanoscale Machining by Field Emission of Electrons from Carbon Nanotubes

2003 ◽  
Vol 125 (4) ◽  
pp. 546-546 ◽  
Author(s):  
C. Trinkle ◽  
P. Kichambare ◽  
R. R. Vallance ◽  
B. Sadanadan ◽  
A. M. Rao ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Field Emission ◽  
Thermal Transport ◽  
Field Emission Of Electrons
Sign in / Sign up

Export Citation Format

Share Document