Surface waves of liquid metal film flow under the influence of spanwise magnetic field

Magnetohydrodynamic effects on liquid metal film flowing along an inclined plate relating to plasma facing components

“…It can be seen from figure 3(a) that without the presence of a transverse magnetic field, the GaInSn film flow behaves like a flow of ordinary fluid, with three-dimensional waves appearing on the surface of the liquid layer due to the high Re in a turbulent state [50]. Once the transverse magnetic field is introduced, similarly to phenomena obtained in our previous studies where the solid walls were electrically insulated [47], the surface structures change dramatically, as shown in figure 3(b); waves become more regular, and tend to be aligned along the direction of magnetic lines, indicating that the turbulent flow state has been transited to a quasi-two dimensional state. This is consistent with the prediction of the theory suggested by Davidson [51] that a magnetic field strongly inhibits the wave moving along the direction of magnetic lines by momentum diffusion, due to Lorentz force and Joule dissipation.…”

“…Therefore, we analyze the film flow in finite positions, and use these data to elaborate on the influence of the transverse magnetic field on flow characteristics. Although we have given an explanation for the nonmonotonic phenomena of thickness variations where there is an increase in Ha in our previous paper [47], this is insufficient, since we did not consider the influence of Hartmann layers and side layers on film flow. In order to qualitatively clarify the phenomenon, we schematically plot the distribution of current lines in the cross section of the film flow in figure 5, based on previous literature [6,52], and our simple simulation for a MHD film flow.…”

“…In our previous studies on MHD effects on liquid metal film flow, the laser profilometer (LP) method was adopted to obtain the film thickness at a fixed-line. It was found that, under the influences of a transverse magnetic field, the free surface waves transit to twodimensional waves; specifically, the surface fluctuation along magnetic field lines are strongly suppressed, leaving the surface waves to propagate in the streamwise direction [45][46][47]. Very recently, Lunz et al [48] modeled the flow of a thin liquid metal film, driven by gravity down a conical substrate in the presence of a strong toroidal magnetic field, and identified values for the relevant situations when the flow is stable, which is important guidance in terms of the design of liquid metal PFCs.…”

“…Although great efforts have been made to study the MHD effects on liquid metal film flow from both the engineering aspects and laboratory perspective, it is still far from being fully understood, and some issues remain to be solved before the first successful liquid metal PFC is realized. Thus, as a continuation of our previous work [47], we adopt the LP to obtain a large amount of film thickness data under different experimental parameters, and try to obtain some useful scaling laws to predict the effect of a magnetic field on liquid metal film flow from an experimental perspective. The remaining part of this paper is organized as follows.…”

Numerical Simulation of Thin-Film MHD Flow for Nonuniform Conductivity Walls

“…Compared to solid PFCs, LM-PFCs have the potential to provide enhanced power-removal capability, by evaporation and relocating the heat with a flowing stream; offer a "self-healing" surface that is practically free from permanent damage by erosion, neutron-induced swelling and plasma irradiation damage; eliminate issues as thermal stresses, local melting and recrystallization; reduce overall system down-time and repair cost and facilitate tritium production, retention, removal and handling [2][3][4]. However, it is still a challenging goal to form a continuously flowing LM film flow with both stable surfaces and uniform thickness due to magnetohydrodynamics (MHD) effects [5].…”