


Streamline Scale: Direct
solution of the equations of motion is the most
fundamental type of modeling. It requires a detailed
description of the pore structure and a computational
technique that can accommodate the complex boundary
conditions. Computational demands constrain the
physical size of the systems. 



Pore Scale: Porescale
modeling employs approximations
to the pore structure and fluid mechanics. The increased computational efficiency
allows much larger length scales to be modeled
(compared to streamline scale modeling), which is
crucial for modeling the discretetocontinuum
transition. 



Continuum Scale: Darcy's
law or similar equations are used for continuumscale
modeling. While essential for many engineering
applications, the drawback is that the
continuum scale parameters in these equation usually
require empiricism, which creates a disconnect between
the model and the governing physics. 



Macroscopic Scale: In
largescale simulations (such as geologic
applications), significant variation in continuumscale parameters
can exist. Computational techniques such as FEM or FDM
allow the domain to be discretized spatially, and
parameters are distributed accordingly. 