Flow and heat transfer characteristics of a droplet impact onto a relatively high temperature thin film during distillation was studied by means of front tracking method. The proposed model was validated by numerical results with analytical solutions. Evolution of gas-liquid interface and heat flux distribution were investigated. Meanwhile, effect of Weber number and dimensionless liquid film thickness on heat transfer was analyzed. It indicates that according to heat flux distribution after impact liquid film can be classified into three zones: The impact zone, the transition zone and the static zone. Forced convection is the main heat transfer mechanism inside the impact zone mainly due to impact. Increasing Weber number or decreasing dimensionless film thickness could enhance heat transfer. With the increase of Weber number, disturbance caused by impact on liquid film strengthens, which makes synergy of momentum and energy more obvious, thus increasing average heat flux between liquid and solid wall, and coronal spray in the impact zone becomes more obvious. The smaller the dimensionless liquid film thickness is, the greater the average heat flux density is, and the longer the heat transfer duration of high heat flux density is.

Kelvin-Helmholtz instability of two-dimensional immiscible incompressible fluid in a sloping tube was numerically simulated with front tracking method. Effects of inclined angles of wall, thickness of velocity gradient layer and Richardson number on development of K-H instability were investigated. It shows that the greater the angle of wall inclination is, the faster the K-H instability develops and the more liquid is rolled up. It was also found that increase of thickness of the velocity gradient layer under the inclined wall presented an inhibitory effect on roll-up of the interface. The greater gravity items of Richardson number is, the slower the interface rolls up. However, surface tension items of Richardson number have weak effect on the growth of interface.

According to the characteristics of compressible flows with wall boundary conditions, a simplified iterative-implicit timeadvancement scheme combined with high order compact difference schemes based on a non-uniform grid system is proposed to solve compressible Navier-Stokes equations, An iteration convergence criterion is given. The computational efficiency is greatly improved. The new scheme is applied to simulate two-dimensional compressible flat-plat laminar boundary layer flows and two-dimensional compressible channel flows.