Pore Resolved Lattice Boltzmann Simulation of Liquid Lithium Flow in Porous Tungsten Structures

Liquid lithium (Li) is considered as a potential plasma facing component (PFC) because of its low core radiative cooling, high heat handling due to evaporation and vapor shielding, as well as self-replenishing capability. A major challenge of Li PFCs is to avoid lithium mass ejection and dryout from jxB force arising from external and thermoelectric currents, respectively. Surface instabilities, such as Rayleigh–Taylor instability, add additional concerns. To solve these challenges, the use of porous structures, mostly made of tungsten (W) or its alloys, is considered. Various porous structures with different porosity and pore geometry have been designed and manufactured for this purpose. To select optimal pore structures for future Li PFC designs, the effect of porosity, pore size, and pore geometry on lithium flow and evaporation within and on the surface of the porous structures need to be considered.    

  

In this work, Lattice Boltzmann (LB) method is applied to simulate Li flow driven by capillary force and/or pressure gradient within porous tungsten structures. D3Q19 Multiple Relaxation Time (MRT) method is used, and the surface tension effect is incorporated using a free energy based method. The simulation is implemented using the open source LB code OpenLB. Three dimensional models of homogeneous and heterogeneous porous structures with different pore sizes and porosity are constructed, and pore-resolved Li flow dynamics on these structures are compared.