TOWING TANK FOR PHYSICAL MODELING OF FLOW PHENOMENA

(Peter) H.-T. Liu

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A towing tank (Fig. 1) was built in 1971 at QUEST Integrated, Inc., formerly Flow Research, Inc.  Extensive physical modeling of flow phenomena was conducted in the tank (1971-1995).  It measured 18 m long, 1.2 m wide and 0.9 m deep.  The tank walls and several bottom panels were made of glass to facilitate flow visualization.  A filling system was designed to prepare a homogeneous or a stratified fluid.  The towing system included two sets of cables, pulleys, drive shafts, motors, and controllers.  The towing system was capable of towing two oil-bearing carriages independently or simultaneously.  The car-riages rode on thin oil films released from four pads supporting the carriages on two tracks, one round and one flat.  The tracks were  aligned such that the vertical displacement of the instrumentation carriage was within 2 mm in the 12-m working section.  A slotwheel consisting of 16 slots was attached to the drive shaft of each motor, and a light emitter/photosensor set was used to measure the towing speed.  The tank was instrumented for measuring high-frequency quantities such as velocity, density, mass concentration and  temper-ature.  For flow visualization, the author has developed a fluores-cent-dye-layer method together with lasersheet Illumination .

Stratified Towing Tank

Highlights of Flow Phenomena Modeled in Towing Tank

Naval Hydrodynamics [1] a. Side view b. Top view c. End views Stratified Wake and Internal Waves Generated by a Self-Propelled Slender Body Stratified Turbulence [2] Evolution of Turbulent Wakes (a) into Strongly Stratified Layers (b) Stereoscopic Tracking of Particle Trajectories [3] Anaglyph of Particle Trajectories Past an Underwater Model (view in stereo with red-and-blue spectacles)

Laminar-Turbulence Transition [4] a. Side view b. Top view c. End view Evolution of Turbulent Spot in Laminar Boundary Layer Modeling of Transport of Air Pollutants [5, 6] Plume Dispersion in a Turbulent Boundary Layer (Orange Shaded) Plume Dispersion in Stable Atmosphere (Kennecott Lead Smelter) Vortex Dynamics [7, 8, 9] Sinusoidal and/or Bursting Instabilities of Wing-Tip Vortices [7] Ground and Shear Effects on Vortex Wakes [8,9]

References

[1] Lin, J.-T. and Pao, Y.-H. (1979) "Wakes in Stratified Fluids," Ann. Rev. Fluid Mech. 11, 317-338.
[2] Liu, H.-T. (1995) "Energetics of Grid Turbulence in a Stably Stratified Fluid," J. Fluid Mech. 296, 127-157.
[3] Liu, H.-T., Weissman, M. A., White, G. B., Miner, G. E., Gustafson, W. T. (1994) "A Stereoscopic System for Measuring 

     Particle Trajectories Past an Underwater Model," Proc. IS&T/SPIE Inter. Sym. on Electronic Imaging: Science and 

     Technology, Paper No. 2177A-28, San Jose, Calif., Feb. 6-10.
[4] Gad-el-hak, M., Blackwelder, R. F., and Riley, J. J. (1981) "On the Growth of Turbulent Regions in a Laminar Boundary Layer,"
     J. Fluid Mech., 110 , 73-95.
[5] Liu, H.-T. (1983) "Application of a Tow Tank for Physical Modeling of Plume Dispersion: Flow Visualization,"  Proc. 3rd Inter.

     Sym.  on Flow Visualization, Ann Arbor, Mich., Sept. 6 - 9.
[6] Liu, H.-T. and Lin, J.-T. "Physical Modeling of Plume Dispersion in Complex Terrain: Neutral and Stable Atmosphere,"  Proc.
     NATO/CCMS 9th Inter. Technical Meeting on Air Pollution and Its Applications, Toronto, Aug. 28 - 31.
[7] Liu, H.-T. (1992) "Effects of Ambient Turbulence on the Decay of a Trailing Vortex Wake,". AIAA J. of Aircraft 29, 255-263.
[8] Liu, H.-T., Hwang, P. A., and Srnsky, R. A. (1992) "Physical Modeling of Ground Effects on Vortex Wakes," AIAA J. of Aircraft

29 , 1027-34.
[9] Liu, H.-T. (1991) "Tow Tank Simulation of Vortex Wake Dynamics," Proc. FAA Inter. Sym. on Wake Vortices , Washington,

     D. C., October, 28-31 

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