Effect of Substrate Microstructure on Thermocapillary Flow and Heat Transfer of Nanofluid Droplet on Heated Wall

In order to reveal the effect of substrate microstructure on heat transfer of nanofluid droplet evaporation, the thermocapillary flow characteristics and heat transfer performance of nanofluid droplet on different substrates are investigated. The two-phase mixture model is used to simulate the nanofluid flow, and three kinds of micro-structured substrates (namely, sawtooth, rectangle, and parabola structures) are considered. The computational results show that micro-structured substrate can affect the temperature and flow field distributions inside the droplet, and the petal structure of isotherm and flow velocity of smooth substrate is larger than that with micro-structured substrates. The average heat flux at droplet surface increases with substrate temperature increasing, the average heat flux with rectangle substrate is larger than smooth substrate, while that of sawtooth and parabola substrate is smaller. With the increase of nanoparticle volume fraction the average heat flux at droplet surface almost increases linearly.