Measurement of locally heated liquid film thickness by a double-fiber optical probe

Preface: Drops, Bubbles, and Thin Films, Special Issue Honoring Professor Oleg Kabov

“…Schlieren images: (top) 6.7 × 68 mm 2 heater, 25% ethyl alcohol, Re = 1, q = 3.9 W/cm 2 ; (bottom) numerical simulations of regular structures formed in gravity-driven films on rectangular heaters (reprinted with permission from AIP, Frank and Kabov, 2006) a function of the distance between a probe and reflecting surface (Zaitsev et al, 2003). Experiments with horizontal liquid layers on locally heated substrates show the formation of a flat, ultra-thin, residual layer prior to the rupture, as shown in Fig.…”

Measurement of Film Thickness on a Curved Surface by Fiber Optic Probe

“…The pool is made of black plastic and is 40 mm deep to avoid reflection from the pool bottom. The calibration is carried out in a similar fashion than Zaitsev, Kabov and Evseev [11]. With the help of a micro screw (with resolution 5 μm) the probe approaches the liquid surface with steps of 50 μm.…”

“…Alekseenko et al [8] had developed a reflecting-type fiber optic sensor to measure the film thickness of liquid nitrogen and an aqueous ethanol solution flowing down on a vertical plate; they used single and pair optical fibers, with the latter having a variation using a glass plate glued on the end of the probe. Zaitsev et al [9], Zaitsev and Kabov [10] and Zaitsev, Kabov and Evseev [11] investigated the rapture of liquid films flowing down an inclined heated plate; measurements of the liquid thickness have been done using reflective-type fiber optic. The film was flowing along absolutely flat surface in the described experiments.…”

“…In fact, in case of wavy films reflection problems on the waves will impede making good measurements (Zaitsev, Kabov and Evseev [11]). In the present work the authors use reflective-type fiber optics to measure thickness of the liquid film flowing along a curvilinear surface in 2 different locations.…”

Mapping of the Marangoni effect in soap films using Young's double-slit experiment

“…Such an effect can also originate from a temperature gradient at the air/liquid interface and is sometimes called Rayleigh-Bénard convection [6,7] when it is linked to thermal convection. Whereas this effect is often invoked, quantitative measurements are scarce [8][9][10][11][12][13][14][15][16][17]. These measurements have been mainly performed, directly using either the naked eye, or with the help of a microscope, or using temperature sensitive markers, or probing the film thickness with interference techniques.…”