Streamline-scale modeling consists of solving the equations of motion within the pore space, subject to boundary conditions imposed by the (typically) complex pore structure. It is the most rigorous and detailed approach to modeling fluid flow, but also the most computationally demanding. A number of numerical techniques are available, and the best choice depends on factors ranging from the Reynolds number to the fluid rheology to the pore structure.

Because of the computational demands (and corresponding limitations on domain size), streamline-scale modeling is rarely used directly for engineering problems. However, it is essential for studying fundamental transport processes. The information gained is then incorporated into network models, continuum models, or upscaled by some other method.