Tomographic PIV
20Pages

Tomographic PIV Volumetric Flow Field Imaging - the ultimate solution for quantitative flow visualization -

Bluff body flow: cylinder wake (page 7) 3 Velocity Components in 3 Dimensions: 3D3C PIV, courtesy D. Schanz, DLR Flexible and robust volumetric flow measurement solutions Turbulent flows are 3-dimensional (3D) in nature. While 2D (laser) imaging cannot resolve turbulent flow structures in all three dimensions, tomographic reconstruction techniques using multiple views are capable of capturing instantaneously complex flow structures in all three dimensions. From time-correlated volume images, instantaneous 3D flow fields are derived by applying a 3D correlation technique on volume elements...

In-cylinder volumetric (3D3C) flow field (page 17) 3D reconstruction: voxels in 3D space (page 4) Due to the unique modular imaging concept our FlowMaster Stereo-PIV systems can be upgraded straight forward for 3D tomographic imaging applications. Furthermore, our high speed FlowMaster Tomo-PIV systems allow time-resolved flow field imaging in 3D-space–revealing the complete 4D-information of dynamically changing flows! The unsurpassed performance of LaVision’s FlowMaster Tomo-PIV systems are proven in challenging applications such as turbulent flow studies, animal locomotion and 3D-imaging...

Tomo-PIV Principle Tomographic reconstruction and 3D cross-correlation of voxel intensities Tracer particles within the measurement volume are illuminated by a high power pulsed light source and the scattered light pattern is recorded simultaneously from typically 4 viewing directions using high resolution cameras 1 . The 3D particle distribution is reconstructed by a tomographic reconstruction algorithm (Multiplicative Algebraic Reconstruction Technique, MART) as a 3D light intensity distribution for each voxel 2 . The particle displacement within a chosen interrogation volume is then...

Volume Self-Calibration* High precision camera calibration for 3D reconstruction A precise volumetric calibration based on a calibration target is required for all tomographic imaging applications. For Tomo-PIV the calibration accuracy needs to be better than 0.1 pixel throughout the measurement volume [1, TU-Delft]. Challenge Camera mounts or other mechanical parts are never 100% stiff. Temperature-changes cause extension or contraction of mechanical parts, wind loads or other vibration sources effect the camera adjustment. Unnoticed, in many experiments, the initial volume calibration...

Fluid in Motion Turbulent fluid motion is the dominating flow configuration for nearly all natural flows as well as for technical applications. Details of such complex fluid motion can now be quantitatively visualized in 3D (4D) using (time-resolved) Tomo-PIV e. g. for the validation of CFD-codes. Thus Tomo-PIV marks an important step in experimental fluid mechanics research providing insight into previously unseen fluid dynamic phenomena. 3D structures of shear layer Separated flows and turbulent wakes A high resolution Tomo-PIV system using four 16 Mpixel Imager LX cameras captures the...

Vortex dynamics studies in a cylinder wake. Tomo-PIV reveals the details of the coherent structures in the turbulent wake of a cylinder and describes both velocity and vorticity fluctuations when time-resolved measurements are applied [1, TU-Delft]. Transitional and turbulent jets A 3D pattern of a transitional water jet flow is recorded using time-resolved Tomo-PIV at 1kHz frame rate. Iso-surfaces of vorticity using the Q-criterion and an axial velocity plane within the 3D measurement volume are presented [2, TU-Delft]. Bluff body flow: cylinder wake in water (Reynolds number : 180 – 2500)...

DaVis Easy – Reliable - Approved DaVis - the complete software solution DaVis accompanies all steps of tomographic PIV measurements in a single integrated software: camera and laser control, external triggering, recording, calibration, data analysis, display and data export. Versatile hardware synchronization Open Data Access DaVis controls up to 8 fully synchronized PIV cameras and 4 lasers, ranging from simple time-based trigger schemes to phase locked measurements and time-resolved recording. DaVis provides free interfaces to Matlab® (also on Mac OS® and Linux®), Tecplot® and a C++...

Algorithms DaVis Tomo-PIV: an ongoing process of innovations The first publication in 2006 triggered a real gold rush in the scientific community. This rush is best documented by the ever growing number of publications, dealing with the development and, more and more, with the application of tomographic PIV Taking an active part in the ongoing process of innovation, our strategy is to make the benefits of innovation available in the easy-to-use environment of DaVis. Major milestones in this innovative process, that directly found their way in the DaVis software, include: 4 robust volume...

Aerodynamic wake flow of a flying locust Volumetric flow imaging is a major step forward in our understanding of turbulent flows induced by flying animals and thereby the mechanics of their locomotion. Animal flight cannot be captured time averaged. Time-resolved recordings with synchronized high speed cameras are essential to reveal the full space-time information. Time-resolved Tomo-PIV measurements are applied in the wake flow of a tethered locust flying in a wind tunnel at a wind speed of 3.3 m/s. The Tomo-PIV imaging system consists of 4 high speed cameras (HighSpeedStar 3G)...

Hydrodynamic footprint of a swimming Daphnia The hydodynamic footprint of small swimming organisms such as the zooplankton Daphnia is – although small in size – affecting the ecosystem in many ways like feeding strategies and local water transport. The hydrodynamic trails of a freely swimming Daphnia in still water are successfully investigated applying time-resolved Tomo-PIV [1, LaVision]. 3D reconstruction of swimming Daphnia The turbulent and time-resolved flow fields of an upward swimming Daphnia in a test aquarium are recorded using four 5 Mpixel Imager SX 5M cameras. Apparently,...