VolumeMapper^© is a newly-patented velocimetry system that allows for true 3D whole field velocity measurements. This system allows for real-time (30 frames per second) acquisition of images of the desired volume using VioCam, the 3D camera, thereby allowing for instantaneous and sequential volumetric data acquisition. Volumetric velocity measurements are done using VioFlow, the flexible and user-friendly PC-based software. Further statistical modules of VioFlow allow the user to calculate statistical quantities such as averages, standard deviations, Reynolds¼ stresses, and various other correlations, to developing more insight into the studies at hand. VolumeMapper^© does not need any time-consuming multi-image calibration as found in stereo DPIV systems, and is therefore easy to setup and use.

Experimental setup of flow around a propeller.

  The operation of VolumeMapper^© is based on the simple yet clever image defocusing principles. The images are captured using the VioCam camera, which comprises 3 CCDs. The instantaneously captured images are then used to identify location of the particle tracers. From the motion of these particle tracers, the whole field velocity is finally inferred.

VioCam's size makes it easily portable. It is light enough to mount onto standard optical rails and mountings.

  VioFlow is made to be easy to use. Both interactive and automated modes are available. The interactive mode allows the user to properly select experimental parameters, such as volumes of interest, voxel sizes, voxel step sized, number of images to process, laser setup and control, etc. Once these are set, the automated mode is then used to acquire sequential three-dimensional images without interruption. Further data processing allows for the calculation of the velocity field, which can be presented in various forms, as shown below.

Volumetric velocity field about the propeller

Slice of data taken from cubic data shown above, showing 3D vectors within the slice.

Camera size: 16 cm diameter by 25 cm length
Camera CCD array size: 1024 * 1024 * 8 bits
Number of CCDs: 3
Volume of interrogation: 10 cm * 10 cm * 10 cm
Image acquisition rate: 30 f/s
Data Presentation formats:

• Tecplot
• MATLAB
• Iris Explore