Proposition of an optical arrangement for interface reconstruction between stratified liquids

We propose a non-intrusive optical method to reconstruct the boundary between the two immiscible liquids under the well separated interfacial configurations. Silicon based PIN (a diode with p-type semiconductor, a lightly doped intrinsic region and an n-type region) photodiodes are used in reverse biased photovoltaic mode and extent of attenuation in the intensity of light is employed to relate the phase fraction (h/b) with obtained current signals. Phase fraction is found to have exponential relationship with the non-dimensional optical signals and is used to reconstruct the interface profile for different phase associations. The optically acquired interface profiles are in close agreement with the visual inspections for both the inclined and curved phase boundaries. Moreover, the present system is found to capable of characterizing the transient variations of the interface. This has been examined by successful prediction of interface oscillations and transient, random wavy profiles. It has also been established that preset photodiode array could be employed for measurement of flow rates and local phase fractions under the stratified regime.