This paper presents a computational study of entrainment characteristics in
the near-field of gas jets under atmospheric and Diesel conditions and spr
ays under Diesel conditions. Computed flowfield information is used to esti
mate the rate of mass entrainment rate constant is compared to experimental
results in the literature. It is found that the computed values of the con
stant in the near-field are less than the values in the self-similar region
of the jet with the values increasing monotonically from the orifice to th
e self-similar region. These results are consistent with experimental resul
ts. In the case of sprays, it is found that it is difficult to arrive at fi
rm conclusions because the results are sensitive to several parameters that
are not well known and to the numerics. The computed results for sprays ar
e also discussed relative to measurements in sprays quoted in the literatur
e. [S0098-2202(00)00802-6].