Closure to “Discussion of ‘Potential Flow Model for an Impulsively Started Circular Cylinder’” (1977, ASME J. Appl. Mech., 44, p. 187)

1977 ◽  
Vol 44 (1) ◽  
pp. 187-187
Author(s):  
H. T. Yang ◽  
M. Bar-Lev
Keyword(s):  
Circular Cylinder ◽  
Potential Flow ◽  
Flow Model ◽  
Potential Flow Model

Performance of a Propeller in a Wake and the Interaction of Propeller and Hull

1965 ◽  
Vol 9 (02) ◽  
pp. 1-36
Author(s):  
Quentin Wald
Keyword(s):  
Potential Flow ◽  
Flow Model ◽  
Practical Case ◽  
Viscous Effects ◽  
Actuator Disk ◽  
Potential Flow Model

Relations are developed which describe the propeller-hull interaction and the efficiency of the wake-operating propeller in the practical case where both potential and viscous effects are important. Momentum equations and the actuator disk representation of the propeller are used. Thrust deduction and efficiency are found to be functions of both the local and the ultimate wake velocity which are, in turn, expressible as functions of the static and total pressures in the propeller plane. The two velocity ratios have opposite effects on the thrust deduction, hence a potential-flow model simulating the velocity at the propeller plane and ignoring the ultimate wake-velocity deficiency arising from viscosity is inadequate.

A Two-Dimensional Potential Flow Model of the Wave Field Generated by a Semisubmerged Body in Heaving Motion

1988 ◽  
Vol 32 (02) ◽  
pp. 83-91
Author(s):  
X. M. Wang ◽  
M. L. Spaulding
Keyword(s):  
Free Surface ◽  
Boundary Conditions ◽  
Potential Flow ◽  
Flow Model ◽  
Second Order ◽  
Two Dimensional ◽  
Third Order ◽  
The Third ◽  
Potential Flow Model ◽  
Good Agreement

A two-dimensional potential flow model is formulated to predict the wave field and forces generated by a sere!submerged body in forced heaving motion. The potential flow problem is solved on a boundary fitted coordinate system that deforms in response to the motion of the free surface and the heaving body. The full nonlinear kinematic and dynamic boundary conditions are used at the free surface. The governing equations and associated boundary conditions are solved by a second-order finite-difference technique based on the modified Euler method for the time domain and a successive overrelaxation (SOR) procedure for the spatial domain. A series of sensitivity studies of grid size and resolution, time step, free surface and body grid redistribution schemes, convergence criteria, and free surface body boundary condition specification was performed to investigate the computational characteristics of the model. The model was applied to predict the forces generated by the forced oscillation of a U-shaped cylinder. Numerical model predictions are generally in good agreement with the available second-order theories for the first-order pressure and force coefficients, but clearly show that the third-order terms are larger than the second-order terms when nonlinearity becomes important in the dimensionless frequency range 1≤ Fr≤ 2. The model results are in good agreement with the available experimental data and confirm the importance of the third order terms.

scholarly journals Explosions at the water surface

2014 ◽  
Vol 752 ◽  
pp. 123-139 ◽  
Author(s):  
Adrien Benusiglio ◽  
David Quéré ◽  
Christophe Clanet
Keyword(s):  
Cylindrical Cavity ◽  
Potential Flow ◽  
Water Surface ◽  
Flow Model ◽  
Maximum Size ◽  
Air Cavity ◽  
Open Tube ◽  
Large Pool ◽  
Potential Flow Model

AbstractWe study the shape and dynamics of cavities created by the explosion of firecrackers at the surface of a large pool of water. Without confinement, the explosion generates a hemispherical air cavity which grows, reaches a maximum size and collapses in a generic w-shape to form a final central jet. When a rigid open tube confines the firecracker, the explosion produces a cylindrical cavity that expands without ever escaping the free end of the tube. We discuss a potential flow model, which captures most of these features.

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