Here, ~z ¼ z=R0 and r~ ¼ ~z=R0 are the reduced jet length and
jet radius, respectively, and the key dimensionless group parameters
in the problem are the Froude number ðFrÞ, the
Weber number ðWeÞ and the Reynolds number ðReÞ, given
by
Fr ¼ t2
0
2R0g
; We ¼ 2R0qt2
0
c ; Re ¼ 2R0qt0
g : (2)
These quantities represent, respectively, the relative effects
of gravity ðgÞ, surface tension ðcÞ, and viscosity ðgÞ in comparison
to inertia, with each defined to be large when inertial
effects are comparatively large.
Neglecting the surface tension effect, Clarke9 derived an
analytical JSF for viscous fluids in terms of the Airy function.
However, his JSF is valid only for high Re because at
low Re the effect of the surface tension becomes more significant
than the viscosity10 and cannot be ignored.11 Adachi12
analyzed the effects of the fluid viscosity and surface tension
in the asymptotic regions of high and low Reynolds number.
No analytical equation for the JSF over a wide range of all
three dimensionless group numbers is known. For inviscid