In fluid dynamics, the Morton number (Mo) is a dimensionless number used together with the Eötvös number or Bond number to characterize the shape of bubbles or drops moving in a surrounding fluid or continuous phase, c.[1] It is named after Rose Morton, who described it with W. L. Haberman in 1953.
[2][3] The Morton number is defined as where g is the acceleration of gravity,
the difference in density of the phases, and
is the surface tension coefficient.
For the case of a bubble with a negligible inner density the Morton number can be simplified to The Morton number can also be expressed by using a combination of the Weber number, Froude number and Reynolds number, The Froude number in the above expression is defined as where V is a reference velocity and d is the equivalent diameter of the drop or bubble.