Investigation of effect of convection on droplet evaporation with direct numerical simulation method

In order to predict the deformation, variation of temperature, concentration and velocity field during droplet evaporation process, a model has been built with direct numerical simulation method. The interface is captured by the coupled level set and volume-of-fluid(CLSVOF) method. Evaporation process, dynamic properties and grid resolution convergence of the model have been validated. After that, the evaporation of mono component droplet under static and convective condition is studied. The results indicate that convective flow breaks the symmetric structure of temperature distribution in flow direction. Due to convection, internal circulation appears along the vertical axis in liquid phase, which speeds up the heat transfer in liquid phase. However, effect of circulation on droplet heating is uneven and the heating rate in the upper region of droplet is faster than that of the lower region. Dimensionless parameters like Sh number and Nu number, increase significantly under convective condition. Sh number is always greater than Nu number, which reveals that heat transfer rate is always greater than mass transfer rate. Convection accelerates the formation of steady boundary layer surrounding droplet in convection condition owing to the faster speed of stabilization of Sh number and Nu number.