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ABSTRACT
In this study, numerical calculations by single- and two-phase models of nanofluid turbulent forced convection in a three-dimensional wavy channel with uniform wall temperature are investigated. The numerical results for the Nusselt number ratio (Nu/Nu0) show that the heat transfer performance of a symmetric wavy channel performs better than that of an in-line wavy channel. The multi-parameter constrained optimization procedure integrating the design of experiments (DOEs), response surface methodology (RSM), genetic algorithm (GA), and computational fluid dynamics (CFD) is proposed to design the nanofluid turbulent convection of the three-dimensional wavy channel.
Nomenclature
| a | = | wave amplitude, mm |
| A | = | acceleration, m/s2 |
| = | closure coefficients | |
| Cp | = | specific heat, J/kg · K |
| Cf | = | friction coefficient |
| Dh | = | hydraulic diameter, mm |
| fdrag | = | drag function |
| g | = | gravity acceleration, m/s2 |
| h | = | heat transfer coefficient |
| k | = | thermal conductivity, W/m · K |
| k | = | turbulent kinetic energy, m2/s2 |
| Lin | = | upstream length, mm |
| Lw | = | wavelength, mm |
| Lout | = | downstream length, mm |
| Ltotal | = | total length, mm |
| = | average Nusselt number | |
| Nu | = | local Nusselt number |
| P | = | pressure, Pa |
| ΔPo | = | pressure drop of the smooth channel, Pa |
| ΔP | = | pressure drop, Pa |
| PF | = | performance factor |
| q″ | = | heat flux |
| Re | = | Reynolds number, |
| T | = | temperature, K |
| Tin | = | inlet temperature, K |
| V | = | velocity, m/s |
| u, v, w | = | velocity components |
| x, y, z | = | Cartesian x, y, z-coordinates, mm |
| A | = | dimensionless wave amplitude, |
| λ | = | dimensionless wave length, |
| ρ | = | density of the working fluid, kg/m3 |
| μ | = | dynamic viscosity, kg/m · s |
| τ | = | shear stress, Pa |
| φ | = | volume fraction |
| ϵ | = | turbulent energy dissipation rate, |
| σk, σϵ | = | empirical constants in turbulence model equations |
| Subscripts | = | |
| dr | = | drift |
| eff | = | effective |
| bf | = | base fluid |
| in | = | inlet |
| m | = | mixture |
| nf | = | nanofluid |
| p | = | solid particle |
| pw | = | pure water |
| w | = | wall |
Nomenclature
| a | = | wave amplitude, mm |
| A | = | acceleration, m/s2 |
| = | closure coefficients | |
| Cp | = | specific heat, J/kg · K |
| Cf | = | friction coefficient |
| Dh | = | hydraulic diameter, mm |
| fdrag | = | drag function |
| g | = | gravity acceleration, m/s2 |
| h | = | heat transfer coefficient |
| k | = | thermal conductivity, W/m · K |
| k | = | turbulent kinetic energy, m2/s2 |
| Lin | = | upstream length, mm |
| Lw | = | wavelength, mm |
| Lout | = | downstream length, mm |
| Ltotal | = | total length, mm |
| = | average Nusselt number | |
| Nu | = | local Nusselt number |
| P | = | pressure, Pa |
| ΔPo | = | pressure drop of the smooth channel, Pa |
| ΔP | = | pressure drop, Pa |
| PF | = | performance factor |
| q″ | = | heat flux |
| Re | = | Reynolds number, |
| T | = | temperature, K |
| Tin | = | inlet temperature, K |
| V | = | velocity, m/s |
| u, v, w | = | velocity components |
| x, y, z | = | Cartesian x, y, z-coordinates, mm |
| A | = | dimensionless wave amplitude, |
| λ | = | dimensionless wave length, |
| ρ | = | density of the working fluid, kg/m3 |
| μ | = | dynamic viscosity, kg/m · s |
| τ | = | shear stress, Pa |
| φ | = | volume fraction |
| ϵ | = | turbulent energy dissipation rate, |
| σk, σϵ | = | empirical constants in turbulence model equations |
| Subscripts | = | |
| dr | = | drift |
| eff | = | effective |
| bf | = | base fluid |
| in | = | inlet |
| m | = | mixture |
| nf | = | nanofluid |
| p | = | solid particle |
| pw | = | pure water |
| w | = | wall |