A note on added mass of a group of sections in confined fluid: a general conclusion

This paper presents the calculation of the hydrodynamic forces exerted on an oscillating circular cylinder when it moves perpendicular to its axis in infinitely deep water covered by compressed ice. The cylinder can oscillate both horizontally and vertically in the course of its translational motion. In the linear approximation, a solution is found for the steady wave motion generated by the cylinder within the hydrodynamic set of equations for the incompressible ideal fluid. It is shown that, depending on the rate of ice compression, both normal and anomalous dispersion can occur in the system. In the latter case, the group velocity can be opposite to the phase velocity in a certain range of wavenumbers. The dependences of the hydrodynamic loads exerted on the cylinder (the added mass, damping coefficients, wave resistance and lift force) on the translational velocity and frequency of oscillation were studied. It was shown that there is a possibility of the appearance of negative values for the damping coefficients at the relatively big cylinder velocity; then, the wave resistance decreases with the increase in cylinder velocity. The theoretical results were underpinned by the numerical calculations for the real parameters of ice and cylinder motion.

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Influence of Gap Size on Added Mass for Spent Fuel Storage Rack

Volume 2: Plant Systems, Structures, Components, and Materials; Risk Assessments and Management ◽

10.1115/icone26-82595 ◽

2018 ◽

Cited By ~ 1

Author(s):

Daogang Lu ◽

Yu Liu ◽

Shu Zheng

Keyword(s):

Vibration Frequency ◽

Input Parameter ◽

Added Mass ◽

Water Tank ◽

Spent Fuel ◽

Free Standing ◽

Fluid Force ◽

Spent Fuel Storage ◽

Fuel Storage ◽

Spent Fuel Pool

Free standing spent fuel storage racks are submerged in water contained with spent fuel pool. During a postulated earthquake, the water surrounding the racks is accelerated and the so-called fluid-structure interaction (FSI) is significantly induced between water, racks and the pool walls[1]. The added mass is an important input parameter for the dynamic structural analysis of the spent fuel storage rack under earthquake[2]. The spent fuel storage rack is different even for the same vendors. Some rack are designed as the honeycomb construction, others are designed as the end-tube-connection construction. Therefore, the added mass for those racks have to be measured for the new rack’s design. More importantly, the added mass is influenced by the layout of the rack in the spent fuel pool. In this paper, an experiment is carried out to measure the added mass by free vibration test. The measured fluid force of the rack is analyzed by Fourier analysis to derive its vibration frequency. The added mass is then evaluated by the vibration frequency in the air and water. Moreover, a two dimensional CFD model of the spent fuel rack immersed in the water tank is built. The fluid force is obtained by a transient analysis with the help of dynamics mesh method.

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Adapting a Linear Potential Theory Solver for the Outer Hull to Account for Fluid Dynamics in Tanks

Volume 9: Odd M. Faltinsen Honoring Symposium on Marine Hydrodynamics ◽

10.1115/omae2013-10284 ◽

2013 ◽

Cited By ~ 1

Author(s):

Arild Ludvigsen ◽

Zhi Yuan Pan ◽

Peng Gou ◽

Torgeir Vada

Keyword(s):

Fluid Dynamics ◽

Boundary Value ◽

Fem Analysis ◽

Computer Code ◽

Added Mass ◽

Geometrical Shape ◽

Linear Potential ◽

Local Pressure ◽

Local Loads ◽

Outer Solution

The linear boundary value problem for the wave dynamics inside a tank is very similar to the solution for the outer hull. Because of this, the boundary value solver for the outer hull can be re-used for the tank. The oscillating hydrostatic pressure in the tank may also be calculated in the same way as for the outer hull. Thereby, the hydrostatic coefficients from the tank can also be obtained from the outer solution. This makes it, in principle, easy to adapt outer solution computer code to also account for the inner solutions for all the tanks. The procedure is discussed by Newman (2005). We have used it in a different way, isolating the tank solution into more flexible independent sub-runs. This approach provides part-results for the tanks, like added mass and restoring from the tanks. It also has numerical benefits, with the possibility to reuse the calculations for tanks of equal geometrical shape. We have also extended the procedure to account for full tanks without waves and restoring effects. The linear tank fluid dynamics is programmed into a quite general hydrodynamic frequency domain solver, with the possibility of automatic transferring of local loads to structural (FEM) analysis. Results for local loads are presented. A simpler method of quasi-static loading in tanks is discussed, with comparison to the present method. Effects on global motions and local pressure coming from the tank dynamics contributions are pointed out, such as the shifted resonance of the vessel and the added mass which differs from rigid masses of the tanks.

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Effect of Different Input Loading Form on Structure-Born Sound Radiation

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.518-523.3768 ◽

2012 ◽

Vol 518-523 ◽

pp. 3768-3771

Author(s):

Zhi Yong Xie ◽

Qi Dou Zhou ◽

Gang Ji

Keyword(s):

Experimental Data ◽

Forced Vibration ◽

Sound Radiation ◽

Added Mass ◽

Elastic Vibration ◽

Simulation And Experiment ◽

Radiation Induced ◽

Vibration And Sound Radiation ◽

Loading Form ◽

Good Agreement

The exciting force’s accurate measurement of is crucial to the structure-born sound radiation. Forced vibration and sound radiation of the ribbed cylinder is examined in the anechoic room. An approach called added mass and damping method is proposed to calculate the elastic vibration and acoustic field of the cylinder. Results obtained from simulation are show to be in good agreement with the experimental data. Sound radiation induced by different input loading form is examined via simulation and experiment. And the equipollence of force and pressure acting on the base is validated.

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Polynomial approach for calculating added mass for fluid-filled cylindrical shells

Journal of Sound and Vibration ◽

10.1016/j.jsv.2005.06.031 ◽

2006 ◽

Vol 291 (3-5) ◽

pp. 1221-1228 ◽

Cited By ~ 7

Author(s):

B. Vamsi Krishna ◽

N. Ganesan

Keyword(s):

Cylindrical Shells ◽

Added Mass

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DENSITY OSCILLATION FROM NANOSCALE TO MACROSCALE

Modern Physics Letters B ◽

10.1142/s0217984908017229 ◽

2008 ◽

Vol 22 (27) ◽

pp. 2649-2658 ◽

Cited By ~ 4

Author(s):

X. Y. CHEN ◽

Y. LIU ◽

J. M. YANG

Keyword(s):

Molecular Dynamics ◽

Channel Flow ◽

Channel Width ◽

Density Structure ◽

Flux Rate ◽

Confined Fluid ◽

Threshold Channel ◽

Micro Channels ◽

Confined Flow ◽

Density Oscillation

The effect of channel width on the density structure of confined fluid in the nano-/micro-channels is examined by equilibrium molecular dynamics (EMD) simulation. It was found that the density oscillation occurs near the wall in both cases of the macroscale or nanoscale confined flow. There exists a threshold channel width L threshold , when channel width H<L threshold , density oscillates throughout the channel. When H>L threshold , L threshold is constant and about 5–6 molecular diameter long, and the density becomes uniform beyond this threshold layer. A newly defined ch number may serve to be the parameter to compare similarity in the micro-/nano-scale channel flow. Moreover, the effect of the density oscillation on fluid mass flux rate is examined quantitatively. The result shows that the effect should be considered when the channel width is below 5 molecular diameter.

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