ft²/d
square foot per day
Diffusivityexact by definition
The square foot per day is exactly 0.09290304/86400 m²/s. It is the hydrogeologist's unit in the United States, where the coefficient of consolidation and the aquifer diffusivity that governs how fast a pressure change propagates are both tabulated in ft²/day.
Watch out: Transmissivity, which sounds similar and is also reported in ft²/day, is a different quantity: it is hydraulic conductivity times aquifer thickness and has the same dimensions by coincidence rather than by meaning. A ft²/day figure needs its quantity named before it can be used.
| 1 ft²/d | 1.0752667 mm²/s |
Solvers that use diffusivity