Which flow regime must be present for Darcy's Law to be applicable?

Which flow regime must be present for Darcy's Law to be applicable?

• A. Turbulent flow
• B. Laminar flow
• C. Transitional flow
• D. Chaotic flow

Answer: (B)

Darcy's Law applies when flow through a porous medium is viscous-dominated and steady, with inertial effects negligible. This happens in laminar flow through the tiny pores, where fluid moves in smooth layers and the flux is linearly related to the pressure gradient. If the flow becomes turbulent, or even transitional, inertial forces disrupt that simple linear relationship and the basic Darcy equation no longer accurately describes the flow (often needing extensions like Forchheimer's term for higher flow rates). So, the flow regime must be laminar for Darcy's Law to be applicable.

Darcy's Law applies when flow through a porous medium is viscous-dominated and steady, with inertial effects negligible. This happens in laminar flow through the tiny pores, where fluid moves in smooth layers and the flux is linearly related to the pressure gradient. If the flow becomes turbulent, or even transitional, inertial forces disrupt that simple linear relationship and the basic Darcy equation no longer accurately describes the flow (often needing extensions like Forchheimer's term for higher flow rates). So, the flow regime must be laminar for Darcy's Law to be applicable.