Question

At which ONE of the following scales is Darcy's law for fluid flow through a porous medium applicable?

• A. Nano-scale
• B. Molecular-scale
• C. Microscopic-scale
• D. Macroscopic-scale

Hint:

Darcy's law is applicable for laminar flow at the macroscopic scale. It simplifies the complex behavior of fluid movement in porous media.

Answer 1

The Correct Option is D

Darcy's law describes the flow of fluid through a porous medium and is valid when the flow is laminar and the fluid behaves as a continuous, homogeneous medium. This law is applicable primarily at the macroscopic scale, where fluid flow is treated as a bulk movement through a porous medium.
At smaller scales, such as the molecular or microscopic scales, the assumptions of Darcy's law break down because the flow is no longer laminar, and fluid interactions at these scales become more complex (e.g., molecular diffusion, turbulence, etc.). Thus, at the macroscopic scale, Darcy's law is effective as it simplifies the complexities of fluid movement into an averaged flow rate.
Therefore, the correct answer is (D) Macroscopic-scale.