![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 heat transfer characteristics of liquid droplets are influenced by the hydrophobicity of the surfaces. Fluid properties and surface energy play important roles in heat transfer assessment. In the present study, the influence of the contact angle on the flow field developed inside a nanofluid droplet consisting of a mixture of water and carbon nanotubes (CNT) is investigated. Flow field and heat transfer characteristics are simulated numerically in line with the experimental conditions. It is found that the flow velocity predicted numerically is in good agreement with the experimental data. Nusselt and Bond numbers increase at large contact angles and Marangoni force dominates over buoyancy force.
Nomenclature
| Bo | = | bond number |
| Cp | = | specific heat capacity |
| F | = | force exerted on CNT particle (N) |
| g | = | gravity (m/s2) |
| Gr | = | Grashof number |
| k | = | thermal conductivity (W/mK) |
| Lc | = | characteristic length (m) |
| mp | = | CNT particle mass (kg) |
| p | = | pressure (pa) |
| q | = | particle position vector (m) |
| R | = | wetting radius (m) |
| T | = | temperature (K) |
| V | = | velocity (m/s) |
| ∀ | = | volume of droplet (m3) |
| α | = | thermal diffusivity (m2/s) |
| β | = | thermal expansion coefficient (1/K) |
| = | surface tension thermal gradient temperature derivative of surface tension (N/mK) | |
| μ | = | dynamic viscosity (pa s) |
| ν | = | kinematic viscosity (m2/s) |
| ρ | = | density (kg/m3) |
| σ | = | surface tension (N/m) |
| Subscripts | = | |
| CNT | = | carbon nanotubes |
| eff | = | effective |
| W | = | water |
Nomenclature
| Bo | = | bond number |
| Cp | = | specific heat capacity |
| F | = | force exerted on CNT particle (N) |
| g | = | gravity (m/s2) |
| Gr | = | Grashof number |
| k | = | thermal conductivity (W/mK) |
| Lc | = | characteristic length (m) |
| mp | = | CNT particle mass (kg) |
| p | = | pressure (pa) |
| q | = | particle position vector (m) |
| R | = | wetting radius (m) |
| T | = | temperature (K) |
| V | = | velocity (m/s) |
| ∀ | = | volume of droplet (m3) |
| α | = | thermal diffusivity (m2/s) |
| β | = | thermal expansion coefficient (1/K) |
| = | surface tension thermal gradient temperature derivative of surface tension (N/mK) | |
| μ | = | dynamic viscosity (pa s) |
| ν | = | kinematic viscosity (m2/s) |
| ρ | = | density (kg/m3) |
| σ | = | surface tension (N/m) |
| Subscripts | = | |
| CNT | = | carbon nanotubes |
| eff | = | effective |
| W | = | water |
Acknowledgments
The authors acknowledge the support provided by the Deanship of Research at King Fahd University of Petroleum and Minerals (KFUPM), Dhahran, Saudi Arabia, for this work under Research Grant RG1334.