<Tr> <Td> Marangoni number </Td> <Td> Mg </Td> <Td> M g = − d σ d T L Δ T η α (\ displaystyle \ mathrm (Mg) = - (\ frac (\ mathrm (d) \ sigma) (\ mathrm (d) T)) (\ frac (L \ Delta T) (\ eta \ alpha))) </Td> <Td> fluid mechanics (Marangoni flow; thermal surface tension forces over viscous forces) </Td> </Tr> <Tr> <Td> Markstein number </Td> <Td> Ma </Td> <Td> M a = L b l f (\ displaystyle \ mathrm (Ma) = (\ frac (L_ (b)) (l_ (f)))) </Td> <Td> turbulence, combustion (Markstein length to laminar flame thickness) </Td> </Tr> <Tr> <Td> Morton number </Td> <Td> Mo </Td> <Td> M o = g μ c 4 Δ ρ ρ c 2 σ 3 (\ displaystyle \ mathrm (Mo) = (\ frac (g \ mu _ (c) ^ (4) \, \ Delta \ rho) (\ rho _ (c) ^ (2) \ sigma ^ (3)))) </Td> <Td> fluid dynamics (determination of bubble / drop shape) </Td> </Tr> <Tr> <Td> Nusselt number </Td> <Td> Nu </Td> <Td> N u = h d k (\ displaystyle \ mathrm (Nu) = (\ frac (hd) (k))) </Td> <Td> heat transfer (forced convection; ratio of convective to conductive heat transfer) </Td> </Tr>

The ratio of inertial forces to gravity forces