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ABSTRACT
The effects of temperature-dependent thermophysical properties on droplet flow characteristics in a parallel-plate channel at submicron scale are investigated. The dissipative particle dynamics method with many-body (MDPD) and energy conservation (DPDe) configurations (MDPDe) was used. Droplet flows were simulated to study the effects of the temperature difference between top and bottom walls, body force on MDPDe particles, and wall-wetting conditions. The effects on the droplet flow were discussed. Droplet flows with a subzero wall temperature were simulated. An ice layer was formed on the wall. Its thickness and shape changed depending on surface wetting, temperature gradient, and body force.
Nomenclature
| A1, A2 | = | attractive and repulsive strengths in the conservative force |
| Cv | = | specific heat at constant volume, Jkg−1 K−1 |
| C1, C2 | = | constants used in Eq. (20) |
| D | = | diffusivity, m2 s−1 |
| DPD | = | dissipative particle dynamics |
| DPDe | = | dissipative particle dynamics with energy conservation |
| e | = | unit vector |
| f | = | force, N |
| Gs | = | Galilei number |
| gc | = | body force, N |
| K | = | proportionality constant |
| kb | = | Boltzmann constant |
| l | = | length scale, m |
| L | = | latent heat, J |
| Lx, Ly, Lz | = | spacial lengths, m |
| m | = | mass, kg |
| MDPD | = | many-body DPD |
| MDPDe | = | DPDe with MDPD feature |
| ndim | = | number of dimensions |
| Ntot | = | total number of MDPDe particles |
| P | = | pressure, Pa |
| Pr | = | Prandtl number (µ(ρα)−1) |
| Qc | = | counteracting heat flux, Wm−2 |
| r | = | interparticle distance |
| rc | = | cutoff radius |
| Sc | = | Schmidt number, (νD−1) |
| T | = | temperature, K |
| Tm | = | melting or freezing temperature, K |
| t | = | time, s |
| v | = | velocity vector |
| α | = | thermal diffusivity, m2 s−1 |
| β | = | ratio between fluid and solid density |
| γ | = | dissipative strength |
| ϵ | = | internal energy, Jkg−1 |
| ζ, ζe | = | random numbers with zero mean and unit variance |
| κ | = | strength of conductive heat flux |
| κo | = | heat friction coefficient |
| λ | = | thermal conductivity, Wm−1 K−1 |
| µ | = | dynamic viscosity, Pa · s |
| Π | = | dimensionless temperature, (T − T)/(TH − TC) |
| ρ | = | DPDe density |
| = | weighted local density | |
| σ | = | strength of random interactions |
| ω | = | weighting function |
| Subscripts | = | |
| BOT | = | bottom |
| H | = | hot |
| C | = | cold |
| drop | = | droplet |
| ext | = | external |
| i, j | = | indices |
| ref | = | reference |
| s, l | = | solid, liquid |
| TOP | = | top |
| x, y, z | = | direction |
| Superscripts | = | |
| C | = | conservative |
| D | = | dissipative |
| Ch | = | conductive heat |
| Rh | = | random heat |
| Vh | = | viscous heat |
| R | = | random |
| ℜ | = | real |
| sv | = | exponential of dissipative weighting function |
Nomenclature
| A1, A2 | = | attractive and repulsive strengths in the conservative force |
| Cv | = | specific heat at constant volume, Jkg−1 K−1 |
| C1, C2 | = | constants used in Eq. (20) |
| D | = | diffusivity, m2 s−1 |
| DPD | = | dissipative particle dynamics |
| DPDe | = | dissipative particle dynamics with energy conservation |
| e | = | unit vector |
| f | = | force, N |
| Gs | = | Galilei number |
| gc | = | body force, N |
| K | = | proportionality constant |
| kb | = | Boltzmann constant |
| l | = | length scale, m |
| L | = | latent heat, J |
| Lx, Ly, Lz | = | spacial lengths, m |
| m | = | mass, kg |
| MDPD | = | many-body DPD |
| MDPDe | = | DPDe with MDPD feature |
| ndim | = | number of dimensions |
| Ntot | = | total number of MDPDe particles |
| P | = | pressure, Pa |
| Pr | = | Prandtl number (µ(ρα)−1) |
| Qc | = | counteracting heat flux, Wm−2 |
| r | = | interparticle distance |
| rc | = | cutoff radius |
| Sc | = | Schmidt number, (νD−1) |
| T | = | temperature, K |
| Tm | = | melting or freezing temperature, K |
| t | = | time, s |
| v | = | velocity vector |
| α | = | thermal diffusivity, m2 s−1 |
| β | = | ratio between fluid and solid density |
| γ | = | dissipative strength |
| ϵ | = | internal energy, Jkg−1 |
| ζ, ζe | = | random numbers with zero mean and unit variance |
| κ | = | strength of conductive heat flux |
| κo | = | heat friction coefficient |
| λ | = | thermal conductivity, Wm−1 K−1 |
| µ | = | dynamic viscosity, Pa · s |
| Π | = | dimensionless temperature, (T − T)/(TH − TC) |
| ρ | = | DPDe density |
| = | weighted local density | |
| σ | = | strength of random interactions |
| ω | = | weighting function |
| Subscripts | = | |
| BOT | = | bottom |
| H | = | hot |
| C | = | cold |
| drop | = | droplet |
| ext | = | external |
| i, j | = | indices |
| ref | = | reference |
| s, l | = | solid, liquid |
| TOP | = | top |
| x, y, z | = | direction |
| Superscripts | = | |
| C | = | conservative |
| D | = | dissipative |
| Ch | = | conductive heat |
| Rh | = | random heat |
| Vh | = | viscous heat |
| R | = | random |
| ℜ | = | real |
| sv | = | exponential of dissipative weighting function |