mm²/s
square millimeter per second
Diffusivityexact by definition
The square millimetre per second is exactly 10⁻⁶ m²/s. It is the SI-preferred way of writing what lubricant specifications call the centistoke, since 1 mm²/s equals exactly 1 cSt. The factor is exact by definition.
Watch out: Because 1 mm²/s and 1 cSt are the same number, an ISO VG 46 oil is 46 mm²/s at 40 °C. If a datasheet gives one and a calculation wants the other, no arithmetic is needed.
| 1 mm²/s | 1 mm²/s |
Solvers that use diffusivity