Saturated or primed mesh-laid interfaces between a water pool and a convective air stream was studied in an attempt to hydrodynamically simulate the entrainment phenomena in a heat pipe system. Because of the intermittent nature of the entrained sprays, a precise synchronization technique was incorporated with a laser diffraction technique in the measurement of both the onset velocity and the droplet SMDs. Two separate correlations for the entrainment onset velocity and the entrained droplet SMDs (Sauter Mean Diameters) were obtained from experimental data analyzed by Buckingham-PI theorem. The resultant correlations are ρ8L1(Vf8)2/σ = 0.254 (L1/L2)0.466 [μ8/(ρ8σL1)0.5]−0.632 for dimensionless onset velocity, and SMD/L1 = 20.8283 (L1/L2)−0.392
(ρ8L1Vf8/μ8)−0.393 [ρ8L1(Vf8)2/σ]−0.349 for
dimensionless droplet SMDs.