![Sample our Engineering & Technology journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5933/TOC-Subject-Sample-2021-Engineering-Tech.jpg"})
ABSTRACT
The flow and heat transfer characteristics of nanofluids are investigated by nonequilibrium molecular dynamics simulations. Both the effect of chaotic movements of nanoparticle (CMN) on flow properties and its resulting heat transfer enhancement are analyzed. Results show that compared with the base fluid, the effective thermal conductivity of nanofluids is increased, and the increase ratio in the shear flow field is much higher than that in the zero-shear flow field. Based on the models built in this paper, the contributions of increased thermal conductivity and CMN to the heat transfer enhancement of nanofluids are 49.8–68.6% and 31.4–50.2%, respectively.
Nomenclature
| Ar | = | argon atom |
| CMN | = | chaotic movement of nanoparticle |
| Cu | = | copper atom |
| D | = | diameter of nanoparticle |
| f1 | = | contribution of increased thermal conductivity |
| f2 | = | contribution of CMN |
| h | = | mean enthalpy |
| = | unit tensor | |
| = | heat flux vector | |
| kB | = | Boltzmann constant |
| m | = | atom mass |
| N | = | total number of system atoms |
| Nl | = | number of atoms in layer l |
| q | = | computed heat flux |
| q0 | = | added heat flux |
| Δq | = | friction-induced heat |
| rij | = | distance between atoms i and j |
| Tl | = | temperature of layer l |
| v | = | shear velocity |
| V | = | system volume |
| = | center-of-mass velocity of layer l | |
| = | velocity of atom | |
| ε | = | energy parameter |
| λ | = | effective thermal conductivity |
| σ | = | length scale |
| φ | = | LJ potential |
| Subscripts | = | |
| base | = | base fluid |
| nano | = | nanofluid |
Nomenclature
| Ar | = | argon atom |
| CMN | = | chaotic movement of nanoparticle |
| Cu | = | copper atom |
| D | = | diameter of nanoparticle |
| f1 | = | contribution of increased thermal conductivity |
| f2 | = | contribution of CMN |
| h | = | mean enthalpy |
| = | unit tensor | |
| = | heat flux vector | |
| kB | = | Boltzmann constant |
| m | = | atom mass |
| N | = | total number of system atoms |
| Nl | = | number of atoms in layer l |
| q | = | computed heat flux |
| q0 | = | added heat flux |
| Δq | = | friction-induced heat |
| rij | = | distance between atoms i and j |
| Tl | = | temperature of layer l |
| v | = | shear velocity |
| V | = | system volume |
| = | center-of-mass velocity of layer l | |
| = | velocity of atom | |
| ε | = | energy parameter |
| λ | = | effective thermal conductivity |
| σ | = | length scale |
| φ | = | LJ potential |
| Subscripts | = | |
| base | = | base fluid |
| nano | = | nanofluid |
Acknowledgment
This work is supported by National Natural Science Foundation of China (Grant No. 51476019, 51276031, and 51376002).