A numerical study of flow boiling in a microchannel using the local front reconstruction method

The rapid advances in performance and miniaturization of electronic devices require a cooling technology that can remove the produced heat at a high rate with small temperature variations, as is obtained in flow boiling. To obtain insight in flow boiling, we performed numerical simulations in a 200 μm square microchannel using the local front reconstruction method. Besides validation with literature results, a parametric study shows an increasing heat removal rate and bubble growth rate with increasing wall temperature, liquid mass density, and liquid heat capacity and decreasing inlet velocity indicating the importance of phase change compared to convective transport. Finally, the heat transfer in the liquid film is studied using a Nusselt number defined with the film thickness, which is comparable to Nusselt number for falling films on hot surfaces. It is observed that convective effects are more pronounced at the bubble rear compared to the bubble front

Comparison of the local front reconstruction method with a diffuse interface model for the modeling of droplet collisions

In the present study the authors compare two different simulation models for the modeling of droplet collisions. The simulation models are: the Local Front Reconstruction Method (LFRM) and the Diffuse Interface Model (DIM). Results for fully three-dimensional simulations of droplet collisions at relatively high Weber number simulated with both models are presented and compared. Additionally, a detailed analysis of the dissipation and energy transfer processes of the collision is presented. An overall good agreement is seen in the collision outcomes. Some differences are observed in the interface evolution and the energy transfer/dissipation process during the droplet collision. A significant portion of these differences can be attributed to the differences in the configuration of the initial velocity field. Therefore, for the initial configuration a divergence-free vortical velocity field is introduced to achieve a better match between the simulation models. This improves the agreement of the simulation results