Advances in direct numerical simulation for MHD modeling of free surface flows Shin-ichi Satake a, , Tomoaki Kunugi b , Sergey Smolentsev c a Department of Applied Electronics, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan b Department of Nuclear Engineering, Kyoto University, Yoshida, Sakyo, Kyoto 606-8501, Japan c Department of Mechanical and Aerospace Engineering, UCLA, Los Angeles, CA 90095-1597, USA Abstract The utilization of FLiBe (LiF Ã /BeF 2 ) free-surface flow as a chamber protection scheme is considered in advanced nuclear fusion reactor. At the design of the nuclear fusion reactor from the viewpoint of thermofluid research, it would be very important to understand the influence of a magnetic field in turbulent free surface flow. On the other hand, turbulent free surface flow (called open channel flow) by direct numerical simulation (DNS) with non-deformable surface was first succeeded by imposing free-slip and non-slip conditions as velocity boundary conditions at the upper and lower, respectively. After that, the research by DNS has been advanced more, it has been clarified that turbulent structures generated from the lower wall travels to the free surface and affected the mechanism of heat and mass transfer at the free surface. The behavior of the structures is affected by the strong magnetic field in the nuclear fusion reactor. Therefore, a DNS of liquid film cooling in the nuclear fusion reactor is performed by authors, and the relations between a magnetic orientation and turbulent flow statistics are clearly observed. In this paper, the DNS result is introduced, and the trial turbulence modeling for MHD free-surface flow by using the DNS database is also discussed. # 2002 Elsevier Science B.V. All rights reserved. Keywords: Direct numerical simulation; MHD modeling; Free surface flows 1. Introduction The two phase flow in gas and liquid for a nuclear fusion reactor engineering field is studied for the purpose of the application to a magnetic- confinement nuclear fusion reactor by using the liquid metal with the large rate of heat diffusion for many years. The main research subject is to reduce MHD resistance and to protect the degra- dation of heat-conducting characteristic ability with a peculiar the liquid metal flow under a strong magnetic field. Recently, the advanced power extraction (APEX) study [1] in the United States regarding the utilization of FLiBe as a coolant has been investigated. Moreover, people in inertia fusion energy (IFE) [2] look at the utilization of FLiBe free surface flow as a chamber protection scheme. Furthermore, there is other the subjects such as the response of liquid film to momentum transportation (plasma wind) from plasma and the safety for Li and Na fire. It is  Corresponding author. Tel.:  /81-471-24-1501; fax:  /81- 471-22-9195 E-mail address: satake@te.noda.tus.ac.jp (S. Satake). Fusion Engineering and Design 61 /62 (2002) 95 /102 www.elsevier.com/locate/fusengdes 0920-3796/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved. PII:S0920-3796(02)00157-6