Obi Lab.

Jpn.Eng.
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Investigation for complex turbulent flows

Objective

The present research focuses on the clarification of complex turbulent flows with Particle Image Velocimetry (PIV) measurement. We cover nonequilibrium region in the near-wake of a bluff body , the flow around a huge structural object like a bridge and swirling flows like wingtip vortex.

Particle Image Velocimetry(PIV)

In PIV measurement, tracing particles mixed in the flow are taken two pictures between very short time. With digital image processing, particle displacements between two images are calculated.

PIV measurement has following advantages

Results

We tried to measure the tandem flow. Measurement area is the flow field between objects. In this flow field flow separation and backflow occur. With results of PIV measurement,we get Reynolds stress distribution and streamline like below.

While we suceeded in catch the Karman-vortex formation behind square rod. Against periodic flow separation, we took phase average and could get phase averaged turbulent statictical values.The animation is the streamline after taking phase average to the results. Foresight

Now we construct the Stereo-PIV system for the measurement of 3D complex turbulent flows.

Related publications

  1. Obi, S., Tokai, N., in press. The pressure-velocity correlation in oscillatory turbulent flow between a pair of bluff bodies, International Journal of Heat and Fluid Flow,27,768-776
  2. Tokai, N., Obi, S., 2005. Oscillatory turbulent flow around a pair of square cylinder in tandem, Int. Conf. on Jets, Wakes and Separated Flows, Toba-shi, Mie, 527-532
  3. Obi, S., Tokai, N, Sakai, K., 2005. The role of pressure-velocity correlation in oscillatory flow between a pair of bluff bodies, ERCOFTAC International Symposium on Engineering Turbulence Modelling and Measurements, Sardinia, 481-490
  4. Sakai, K., Maeda, T., Obi, S., 2002. Evaluation of the pressure-velocity correlation in turbulent wake of a rectangular cylinder, 5th JSME-KSME Fluids Engineering Conference, Nagoya
  5. Yoshioka, S., Obi, S., Masuda, S., 2001. Turbulence statistics of periodically pertubed separated flow over backward-facing step. International Journal of Heat and Fluid Flow, 22, 393-401
  6. Yoshioka, S., Obi, S., Masuda, S., 2001. Organized vortex motion in periodically perturbed turbulent separated flow over a backward-facing step. International Journal of Heat and Fluid Flow, 22, 302-307