AN INTRODUCTION TO 2-CCD DIGITAL PARTICLE IMAGE VELOCIMETRY SYSTEM AND ITS APPLICATION IN OCEAN ENGINEERING

The basic principle of particle image velocinmetry (PIV) is described. When a PIV image is analyzed by the method of auto-correlation, there is a direction ambiguity of 180 degrees iii velocity measurement. The problem can be solved by using ''Image Shifting Technique'', but this makes devices much complicated and difficult to control. A new arrang ement of 2-CCD (Charge Coupled Device) fully digitized PIV system, whi ch can also solve the problem successfully, is introduced in the paper . As an example of application of the system, an experimental result o f flow field around a horizontal cylinder in wave is presented.