  The dynamic properties of fluid, including density, surface tension,
diffusivity and viscosity, are temperature-dependent and can significantly
influence the flow dynamics of mesoscopic non-isothermal systems. To capture
the correct temperature-dependence of a fluid, a many-body dissipative particle
dynamics model with energy conservation (mDPDe) is developed by combining the
temperature-dependent coefficient of the conservative force and weighting terms
of the dissipative and random forces. The momentum and thermal diffusivity,
viscosity, and surface tension of liquid water at various temperatures ranging
from 273 K to 373 K are used as examples for verifying the proposed model.
Simulations of a periodic Poiseuille flow driven by body forces and heat
sources are carried out to validate the diffusivity of the present model. Also,
a steady case of heat conduction for reproducing the Fourier law is used to
validate the thermal boundary conditions. By using this mDPDe simulations, the
thermocapillary motion of liquid water nanodroplets on hydrophobic substrates
with thermal gradients is investigated. The migration of the droplet is
observed on flat substrates with gradient temperature. The velocity of the
migration becomes larger for higher temperature difference, which is in
agreement with the present theoretical analysis and DVDWT simulations. The
results illustrate that the modified model can be used to study Marangoni
effect on a nanodroplet and other heat and mass transfer problems with free
interface.
