Simultaneous Measurement of Liquid Surface and Wave Velocities for Falling Liquid Films

We propose a simultaneous measurement of liquid surface and wave velocities for falling liquid films on inclined wall The liquid surface velocity was measured using a non―intrusive technique called as laser tagging method by photochromic dye. The movement of the dye trace tagged by UV laser(λ=355nm)was recorded by a high speed video camera and analyzed together with the movement of wave passing over the dye trace. As a result,velocity difference between wave and liquid film before the wave passing over was found to increase with increasing wall inclination angle.