32 research outputs found
How to Calculate Tortuosity Easily?
Tortuosity is one of the key parameters describing the geometry and transport
properties of porous media. It is defined either as an average elongation of
fluid paths or as a retardation factor that measures the resistance of a porous
medium to the flow. However, in contrast to a retardation factor, an average
fluid path elongation is difficult to compute numerically and, in general, is
not measurable directly in experiments. We review some recent achievements in
bridging the gap between the two formulations of tortuosity and discuss
possible method of numerical and an experimental measurements of the tortuosity
directly from the fluid velocity field.Comment: 6 pages, 8 figure
Study of the convergence of the Meshless Lattice Boltzmann Method in Taylor-Green and annular channel flows
The Meshless Lattice Boltzmann Method (MLBM) is a numerical tool that
relieves the standard Lattice Boltzmann Method (LBM) from regular lattices and,
at the same time, decouples space and velocity discretizations. In this study,
we investigate the numerical convergence of MLBM in two benchmark tests: the
Taylor-Green vortex and annular (bent) channel flow. We compare our MLBM
results to LBM and to the analytical solution of the Navier-Stokes equation. We
investigate the method's convergence in terms of the discretization parameter,
the interpolation order, and the LBM streaming distance refinement. We observe
that MLBM outperforms LBM in terms of the error value for the same number of
nodes discretizing the domain. We find that LBM errors at a given streaming
distance and timestep length are the asymptotic lower
bounds of MLBM errors with the same streaming distance and timestep length.
Finally, we suggest an expression for the MLBM error that consists of the LBM
error and other terms related to the semi-Lagrangian nature of the discussed
method itself