List of Figures
part of Free-surface Wave Interaction with a Horizontal Cylinder
an M.S. thesis by Peter
Oshkai. Department of Mechanical
Engineering and Mechanics. Lehigh University.
Figure 1a: Configuration of experimental system.
Figure 1b: Closeup of the test section.
Figure 1c: Overview of experimental arrangement and principal parameters for wave-cylinder interaction.
Figure 1d: Top view of the test section.
Figure 1e: Detailed schematic of the test cylinder.
Figure 1f: General procedure for image processing.
Figure 2a: Time history of patterns of positive (solid line) and negative (dashed line) concentrations of vorticity and corresponding velocity field and streamline topology for the case of relatively deep submergence of the horizontal cylinder beneath the free-surface wave. Frame number of cinema sequence is designated by N. Nominal submergence of the cylinder is h/D = 1.57. Minimum and incremental values of vorticity are w_min = dw = 3 (1/sec).
Figure 2b: Time history of patterns of positive (solid line) and negative (dashed line) concentrations of vorticity and zoomed-in representations of corresponding velocity fields associated with vortex pairs for the case of relatively deep submergence of the horizontal cylinder beneath the free-surface wave. Frame number of cinema sequence is designated by N. Nominal submergence of the cylinder is h/D = 1.57. Minimum and incremental values of vorticity are w_min = dw = 3 (1/sec).
Figure 3: Illustration of the principal types of trajectories of positive and negative vorticity concentrations. Level of submergence of cylinder beneath the free-surface is h/D = 1.57.
Figure 4: Comparison of selected patterns of instantaneous vorticity with time histories of horizontal Cx and vertical Cy force coefficients for relatively deep submergence of cylinder h/D = 1.57.
Figure 5a: Calculated moments of vorticity (Mw)x corresponding to the horizontal (x) direction force, in which hollow and filled square symbols represent respectively contributions from positive and negative vorticity concentrations. Circular symbol represents net sum of positive and negative contributions. Solid line corresponds to the measured time integral of the horizontal force coefficient. Each frame number N corresponds to an instantaneous PIV image. Level of submergence of cylinder is h/D = 1.57.
Figure 5b: Calculated moments of vorticity corresponding to the vertical (y) direction of force, in which hollow and filled square symbols represent respectively contributions from positive and negative vorticity concentrations. Circular symbol represents net sum of positive and negative contributions. Solid line corresponds to the measured time integral of the vertical force coefficient. Each frame number N represents an instantaneous PIV image. Level of submergence of cylinder is h/D = 1.57.
Figure 6: Contributions of major concentrations of vorticity A, B, A', B', C and D to the moments of vorticity corresponding to the x and y direction forces. Level of submergence of cylinder beneath the free-surface is h/D = 1.57.
Figure 7a: Comparison of instantaneous patterns of vorticity at the same frame numbers N = 7 and 9 for varying levels of submergence h/D = 1.57, 0.55, and 0 of the cylinder beneath the free-surface. Frame N = 7 represents the instant where the crest of the free-surface wave is above the cylinder. Minimum and incremental values of vorticity are w_min = dw = 3 (1/sec).
Figure 7b: Comparison of instantaneous patterns of vorticity at the same frame numbers N = 11 and 15 for varying levels of submergence h/D = 1.57, 0.55, and 0 of the cylinder beneath the free-surface. Frame N = 15 represents the instant at which the trough of the free-surface wave is above the cylinder. Minimum and incremental values of vorticity are w_min = dw = 3 (1/sec).
Figure 7c: Comparison of instantaneous patterns of vorticity at the same frame numbers N = 17 and 19 for varying levels of submergence h/D = 1.57, 0.55, and 0 of the cylinder beneath the free-surface. Minimum and incremental values of vorticity are w_min = dw = 3 (1/sec).
Figure A-1: Characteristic velocity calculation.
Figure A-2: Mean velocity vectors (upstream region) for the stationary cylinder case.
Figure D-1: Oscillations of a cylinder in an incident wave: effects of phase shift.
Figure D-2: Images for maximum Fx case. Oscillating cylinder.
Figure D-3: Images for minimum Fx case. Oscillating cylinder.
Figure E-1: Velocity fields and streamline topology at two instants of time for two different depths of submergence.
Figure E-2: Images corresponding to frame number 9. Stationary cylinder. Various depths of cylinder submergence.
poshkai@me.uvic.ca
