[srv537]

i am simulating jet breakup in crossflow, i am using air as crossflow and liquid water as jet.
i cant able to decide about surface tension model.
in fluent tutorial it is mention that
The importance of surface tension effects is determined based on the value of two dimensionless quantities: the Reynolds number, Re, and the capillary number, Ca; or the Reynolds number, Re, and the Weber number, We. For Re , the quantity of interest is the capillary number:




and for Re , the quantity of interest is the Weber number:




where is the free-stream velocity. Surface tension effects can be neglected if Ca or We .



in my case Re is greater than 1 so weber number is the criteria but i have two fluid (water and air) so two density and two velocity, which should i use to calculate weber number and what should be the length(inlet height, jet diameter and length of the channel)


thanks in advance