Begell House Inc.
Journal of Flow Visualization and Image Processing
JFV
1065-3090
3
4
1996
VISUALIZATION OF NATURAL AND COMBINED CONVECTION USING STREAMLINE GENERATORS
247-252
10.1615/JFlowVisImageProc.v3.i4.10
Aristeu
Silveira-Neto
Faculdade de Engenharia Mecanica, Universidade Federal de Uberlandia, Av. Joao Naves de Avila 2121, 38408-144 Uberlandia, Brazil
Paulo J. T.
Mendes
Federal University of Uberlândia, Department of Mechanical Engineering, 38400-206, Uberlândia MG, Brazil
Akiko
Nishimoto
Federal University of Uberlândia, Department of Mechanical Engineering, 38400-206, Uberlândia MG, Brazil
A new streamline tracer method is presented and applied to visualize natural and combined convection. The method is easy and inexpensive to use. Low-velocity two-dimensional flows can be clearly visualized. In the present work the natural and combined convection around a horizontal and heated cylinder has been visualized. The natural convection presents a symmetric flow, and the combined convection is not symmetric due to the rotation of the cylinder.
RECONSTRUCTION OF THREE-DIMENSIONAL DENSITY DISTRIBUTION FROM THE LIMITED PROJECTION IMAGES WITH GENETIC ALGORITHM
253-263
10.1615/JFlowVisImageProc.v3.i4.20
Koji
Okamoto
Graduate School of Frontier Science, Nuclear Engineering Research Laboratory, The University of Tokyo, Japan
D.
Tsuru
Nuclear Engineering Research Laboratory, University of Tokyo, Tokai-mura, Ibaraki, Japan
Motoo
Fumizawa
Japan Atomic Energy Research Institute, Tokai-mura, Ibaraki, Japan
Measurement of three-dimensional density distributions in a transient unstable stratified flow is important for the safety analysis on the advanced-type nuclear power plant. Three-dimensional density distribution can be reconstructed using computer tomography techniques from interferogram images. However, in the transient experiment, only two or four interferogram images from different angles can be taken. Conventional tomography techniques have a low accuracy with few interferogram images, because the information of the projection is not enough for the reconstruction. In this study, a new three-dimensional reconstruction technique was proposed. In this technique, the genetic algorithm was introduced to reconstruct the whole field from a few interferogram images.
CORRECTION OF PIV IMAGE BIASING USING TWO CO-ROTATING MIRRORS
265-277
10.1615/JFlowVisImageProc.v3.i4.30
Kenneth D.
Kihm
Texas A&M University College Station, TX; and Micro/Nano-Scale Fluidics and Energy Transport Laboratory, University of Tennessee, Mechanical, Aerospace and Biomedical Engineering Department, Knoxville TN 37996-2210, USA
S. D.
Lee
Department of Mechanical Engineering, Seoul National University, Seoul 151-742, Korea
Suk Ho
Chung
Clean Combustion Research Center King Abdullah University of Science and Technology Thuwal,
Saudi Arabia
The rotating mirror configuration in particle image velocimetry (PIV) is generally used to provide an artificial image shift to resolve the directional ambiguities for the recorded particle image pairs. However, the reflected image from the rotating mirror inevitably creates normal velocity components with respect to the image plane, and this normal component causes spatially distributed systematic image errors. A potential solution for the problem is proposed to replace the single rotating mirror with two co-rotating mirrors. The use of two co-rotating mirrors reduces the image biasing with desired amounts of the velocity shift available, and, at the same time, makes the image biasing uniform on the entire image field so that analytical corrections for the biasing are readily feasible. Detailed imaging kinematics of the suggested method are presented to improve the design of practical PIV systems. Also presented is experimental confirmation of the image correction using two co-rotating mirrors.
A KINEMATIC STUDY OF HYDRODYNAMIC FLOWS USING PARTICLE STREAK VELOCIMETRY TECHNIQUE
279-298
10.1615/JFlowVisImageProc.v3.i4.40
Alain
Texier
LE.A./LM.F. (U.M.R. CNRS n°6609), Bâtiment de Mécanique-40, avenue du Recteur Pineau-86022 Poitiers Cedex, Université de Poitiers - France
L.
David
Laboratoire d'Etudes Aerodynamiques (LEA), UMR CNRS 6609, Blv. Marie & Pierre Curie, B.P. 30179, 86962 Futuroscope Chasseneuil Cedex, France
Image processing kinematic facilities provide complementary physical analysis for flow visualization studies. Topologicat wake evolution and shed vortices understanding are complemented with full accuracy velocity field measurements followed by precise interpolation, derivative and integrate steps to determine the vorticity, pressure, and streamlines. This visualization and process analysis is applied to the study of the near wake flow around a circular cylinder for a Reynolds number of 1000.
A NEW METHOD OF STREAKLINE TRACING FOR TIME-PERIODIC BIOFLUIDS
299-310
10.1615/JFlowVisImageProc.v3.i4.50
Hao
Liu
Kawachi Millibioflight Project, Japan Science and Technology Corporation (JST), Park Building 3F, 4-7-6 Komaba, Meguro, Tokyo 153, Japan
Keiji
Kawachi
University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo, 153-8405, Japan
A new method of streakline tracing for time-periodic flow has been developed and applied to the visualization processing of biofluids induced by fluid-structure interactions in biomechanics. This method takes advantage of the time periodicity of the forced oscillation biofluids by decomposing the computed velocity field into a Fourier series. Therefore, calculation of streaklines can be implemented in the post-processing separately from the solution to the Navier-Stokes (NS) equations, and hence large reduction of computing time and memory for storage requirements is achieved. The method is formulated and executed in computational space and is capable of dealing with complex external flows around swimming and flying animals with moving/deforming boundaries.
BUBBLY FLOW DYNAMICS STRUCTURE USING PARTICLE IMAGE VELOCIMETRY
311-318
10.1615/JFlowVisImageProc.v3.i4.60
Yassin A.
Hassan
Department of Nuclear Engineering, Texas A&M University, College Station, TX 77843, USA
William D.
Schmidt
Department of Nuclear Engineering, Texas A&M University, College Station, TX 77843, USA
Javier
Ortiz-Villafuerte
Department of Nuclear Engineering, Texas A&M University, College Station, TX 77843, USA
Particle image velocimetry (PIV) is a nonintrusive measurement technique that can be used to study the structure of various fluid flows. PIV is used to measure the time-varying full-field velocity data of a particle-seeded flow field within either a two-dimensional plane or three-dimensional volume. PIV is a very efficient measurement technique because it can obtain both qualitative and quantitative spatial information about the flow field being studied. This information can be processed further into information such as vorticity and pathlines and turbulence over extended areas. Other flow measurement techniques (Laser Doppler Velocimetry, Hot Wire Anemometry, etc.) only provide quantitative information at a single point. PIV can be used to study turbulence structures if a sufficient amount of data can be acquired and analyzed, and it can also be extended to study two-phase flows if both phases can be distinguished. In this study, the flow structure around a bubble rising in a pipe filled with water was studied in three-dimensions. The velocity of the rising bubble and the. velocity field of the surrounding water was measured. Then the turbulence intensities and Reynolds stresses were calculated from the experimental data.
MEASUREMENT AND FLOW VISUALIZATION OF A BEATING BUMBLEBEE WING
319-327
10.1615/JFlowVisImageProc.v3.i4.70
Lijiang
Zeng
Kawachi Millibiqflight Project, Exploratory Research for Advanced Technology (ERATO), Japan Science and Technology Corporation (JST), Pilot Lab., 5-9-1 Tokodai, Tsukuba 300-26, Japan
Hao
Liu
Kawachi Millibioflight Project, Japan Science and Technology Corporation (JST), Park Building 3F, 4-7-6 Komaba, Meguro, Tokyo 153, Japan
Keiji
Kawachi
University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo, 153-8405, Japan
A divergent-ray projection (DRP) method was developed for simultaneously measuring the flapping angle, lag angle, and torsional angle of an insect wing using only one high-speed camera. We applied this method to a bumblebee wing. We then simulated the flows around the beating wing by using a computational fluid dynamics (CFD) model of a bumblebee hovering (forward flight) based on the actual geometry of the wing and the measured kinematics of the beating motion (i.e., the three angles). Our measurement and flow visualization reveal that the beating motion of a bumblebee wing creates highly three-dimensional flows that are extremely sensitive to the kinematics. Such sensitivity means that both an accurate description of the beating motion and an appropriate visualization of the flows are important in studying the flight performance of it.
Author Index to Volume 3
333
10.1615/JFlowVisImageProc.v3.i4.80