SOME ADVANCES IN NUMERICAL SIMULATIONS OF MULTISCALE HEAT TRANSFER PROBLEMS AND PARTICULARLY FOR BOILING HEAT TRANSFER

A system or process that covers several geometric or time scales is called a multiscale problem. The multiscale problems in thermo-fluid science and engineering may be divided into two categories: multiscale process and multiscale system. In the multiscale process, phenomena in different regions of the solution domain are governed by different equations and solved by different numerical approaches. And, the solutions are exchanged or coupled (interpolated) at the interfaces of two neighboring regions. Whereas for the multiscale system, the entire domain is governed by the same equation and solved by the same numerical method. However, the grid sizes in different regions may have one to two order magnitude differences, and a special numerical technique should be developed. The transport phenomena in a proton-exchange membrane fuel cell (PEMFC) and cooling of a data center are, respectively, the examples of the multiscale process and multiscale system. This review paper focuses on the multiscale process and includes four parts: (i) introduction to multiscale heat transfer and fluid flow problems, (ii) pore-scale simulation, (iii) interface capturing method of VOSET, and (iv) further research needs for multiscale simulation of boiling heat transfer. These four parts are presented in order.