Simultaneous PIV and pulsed shadow technique in slug flow: a solution for optical problems

Liquid re-circulation in turbulent vertical pipe flow behind a cylindrical bluff body and a ventilated cavity attached to a sparger

“…Many authors have observed that there is a vortex behind bluff bodies (Taylor and Whitelaw, 1984) or in the wake of Taylor (slug) bubbles (Nogueira et al, 2000;Bugg and Saad, 2001;van Hout et al, 2002;Shemer, 2003;Nogueira et al, 2003). It is observed in Figs.…”

Film and slug behaviour in intermittent slug–annular microchannel flows

“…The usual methods of matching the refractive index of the fluid and the wall and submerging the curved test section in a bath of the same fluid (Budwig, 1994;Nogueira et al, 2003;Hao et al, 2007) could not be employed with the sapphire/ water combination. However, for the outside air-sapphire interface, we employed a refractive index-matching (RIM) system in which the space between a planar sapphire window and the curved sapphire tube was filled with a fluid having the same refractive index as sapphire (R.I.¼1.76070.0005, Cargille Laboratories).…”

Pulsed operation of high-power light emitting diodes for imaging flow velocimetry

“…This makes the LED particularly interesting for utilization as a pulsed light source in imagebased diagnostics. The literature reports the use of LEDs in schlieren imaging [3], bubble shadowgraphy [4][5][6], shadow velocimetry [7], PIV [8] as well as micro-PIV [9]. If operated in a forward scatter shadowgraphy arrangement short duration pulses of τ p < 250 ns enable high-speed shadowgraphy in the 100 kHz range of kerosene sprays at high magnification [10].…”