Cycle-to-cycle variations in the wave forces on horizontal cylinders

Conference · Sat Jan 01 04:00:00 EST 1983 · Am. Soc. Mech. Eng., (Pap.); (United States)

OSTI ID:5432414

Ramberg, S E; Niedzwecki, J M

Measurements of the wave forces on horizontal cylinders in laboratory waves are presented. The horizontal and vertical force components are examined together so that variations and limitations in the traditional Morison methods can be identified. Average magnitudes of the wave forces and the force transfer coefficients are compared to wave-bywave values for up to ten consecutive wave cycles in an effort to resolve conflicting reports of cycleto-cycle irregularities in harmonic flow-induced forces. The observed influences of different water particle orbit shapes are presented as well. The experiments, necessarily at low Reynolds number, provide results that encompass a wide range of wave/cylinder conditions. The frequency parameter ranges from 90 to 350, the orbit eccentricity varies from about 0.5 to 1.0 and the Keulegan-Carpenter number ranges from 0.5 to 30. It was found that cycle-to-cycle force variations occur routinely at moderate Keulegan-Carpenter numbers and that these actual force variations are overstated by the calculated variations in C /SUB M/ and C /SUB D/ .

• Research Organization: Naval Research Laboratory, Washington, DC
• OSTI ID: 5432414
• Report Number(s): CONF-830108-
• Conference Information: Journal Name: Am. Soc. Mech. Eng., (Pap.); (United States)
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
423000* -- Engineering-- Marine Engineering-- (1980-)
BENCH-SCALE EXPERIMENTS
CYLINDERS
FLUID MECHANICS
FREQUENCY ANALYSIS
GRAVITY WAVES
HYDRODYNAMICS
MEASURING METHODS
MECHANICS
REYNOLDS NUMBER
VARIATIONS
WATER WAVES
WAVE FORCES