An experimental study of impulsively started turbulent axisymmetric jets

Implications of Upwells as Hydrodynamic Jets in a Pulse Jet Mixed System

“…These values were determined by asserting the jet to be a right cylindrical cone of radius  c through its full traverse from the virtual origin upward (to the right in the plot) in the 12.75 ft vessel. The water curves give values of  c of 0.112-0.123 (see Table 2.1) in approximate agreement with the literature values of  c of approximately 0.065 to 0.14 (see Rajaratnam 1976;Bird et al 2002;Bajpai and Tirumkudulu 2008;Crapper and Baines 1976;Shekarriz et al 1996). Notably, the fractional width is approximately 10% to 20% of the vessel radius but may vary between vessel sizes.…”

“…(The velocity data includes a 2.25 s delay due to a signal processing constraint not adjusted herein.) The steepest slope (a measure of the penetration front of the jet similar to the thresholding of Bajpai and Tirumkudulu 2008) is registered at the seam 3.9 s after the pulse begins, 5.1 s at 34 inches above the seam, and 6.5 s at 68 inches above the seam. These times represent the transience or celerity of the jet; celerity means rapidity or swiftness of motion.…”

Large-eddy simulation of starting buoyant jets

“…The starting pure jet is a configuration of critical importance for many engineering applications (in combustion for example) and has been studied by a number of investigators. Generally, the jet is found to penetrate linearly with time in the PFD [7,8], and with the square root of time in the downstream self-similar phase [9][10][11][12] of the PDF. The other extreme of a starting lazy plume has been studied by Lundgren et al [13], Alahyari and Longmire [14], and Pottebaum and Gharib [15].…”

Particle Image Velocimetry of Human Cough

“…In their studies of transient jets, Johari et al (1997) and Bajpai and Tirumkudulu (2008) use a nondimensional time scale based on steady-state jet speed V j and diameter D of tV j /D. This can be interpreted as a nondimensionalized equivalent piston stroke of length L, L/D.…”

“…Although the starting jet is acknowledged to be not self-similar, particularly in its initial stages and close to the head of the jet, experimental and theoretical analyses often explore the application of steadystate turbulent jet scalings. Several such recent works have had success in predicting the evolution of the tip of the jet (Johari et al 1997;Hill and Ouellette 1999;Song and Abraham 2003;Cossali et al 2004;Ai et al 2005;Bajpai and Tirumkudulu 2008).…”