A lattice Boltzmann model for noble gas diffusion in solids: The importance of domain shape and diffusive anisotropy and implications for thermochronometry

摘要: Abstract Thermochronometry based on radiogenic noble gases is critically dependent upon accurate knowledge of the kinetics diffusion. With few exceptions, complex natural crystals are represented by ideal geometries such as infinite sheets, cylinders, or spheres, and diffusivity assumed to be isotropic. However, physical boundaries generally do not conform diffusion within some known anisotropic. Our failure incorporate complexities into diffusive models leads inaccuracies in both thermal histories parameters calculated from fractional release data. To address these shortcomings we developed a code lattice Boltzmann (LB) method model 3D having isotropic, temperature-independent anisotropic, temperature-dependent anisotropic diffusivity. In this paper outline theoretical basis for LB highlight several advantages relative more traditional finite difference approaches. The code, along with existing analytical solutions simple geometries, used investigate affect intrinsic crystallographic features (e.g., crystal topology anisotropy) novel approximating topologies anisotropy presented.