Modeling of Deepwater-Type Rectangular Tuned Liquid Damper With Submerged Nets

1999 ◽  
Vol 121 (4) ◽  
pp. 413-422 ◽  
Author(s):  
S. Kaneko ◽  
O. Yoshida
Keyword(s):  
Hydrodynamic Force ◽  
Wave Theory ◽  
Finite Amplitude ◽  
Tuned Liquid Damper ◽  
Damping Force ◽  
Dissipation Energy ◽  
Actual Structure ◽  
High Rise ◽  
Modeling Methodology ◽  
Liquid Depth

An analytical model for describing the effectiveness of deepwater-type tuned liquid damper (TLD) with submerged nets for suppressing horizontal vibration of structures is proposed. TLD is a damping device for suppressing the vibration of long-period structures such as high-rise buildings, tall towers, the pylons of cable-stayed bridges, and so on. The damping force is created by the hydrodynamic force caused by the sloshing of water contained in rectangular tanks located on top of such structures. In this study, we proposed the dynamical model for analyzing deepwater-type TLD (DTLD) where the liquid depth is deep compared with the length of the rectangular tank. In particular, the effect of hydraulic resistance produced by submerged nets installed in the tank is examined intensively. In the analysis of DTLD, employing finite amplitude wave theory, we obtained the hydrodynamic force and the dissipation energy by using Galerkin method, taking the effect of submerged nets into account. The calculated results thus obtained are compared with experimental results, by which the validity of the modeling methodology is confirmed. Finally, the case in which DTLD with nets is installed on an actual structure is investigated both theoretically and experimentally and the performance of DTLD is illustrated.

Dynamical Modeling of Deepwater-Type Cylindrical Tuned Liquid Damper With a Submerged Net

1999 ◽  
Vol 122 (1) ◽  
pp. 96-104 ◽  
Author(s):  
Shigehiko Kaneko ◽  
Yasuo Mizota
Keyword(s):  
Wave Theory ◽  
Finite Amplitude ◽  
Hydrodynamic Forces ◽  
Experimental Results ◽  
Shaking Table ◽  
Cylindrical Tank ◽  
Tuned Liquid Damper ◽  
Amplitude Wave ◽  
Modeling Methodology ◽  
Liquid Depth

An analytical model for describing the effectiveness of a deepwater-type cylindrical tuned liquid damper (TLD) with a submerged net for suppressing horizontal vibration of structures is first proposed. In this study, we performed calculations to estimate the effectiveness of a deepwater-type cylindrical TLD based on a proposed dynamical model and compared with experimental results obtained by shaking table experiments and free oscillation tests. In particular, the effect of hydraulic resistance produced by a submerged net and the liquid depth ratio (the ratio of the liquid depth to the diameter of the cylindrical tank) are examined intensively. In the analysis, employing finite amplitude wave theory and Galerkin method in the case of cylindrical tank, we obtained hydrodynamic forces and the free surface elevations. Then, combining the hydrodynamic forces with the equation of motion of the structure, damped transient responses were calculated. The calculated results thus obtained were compared with the experimental results, by which the validity of the modeling methodology was confirmed. [S0094-9930(00)00101-3]

Modeling of Tuned Liquid Damper With Submerged Nets

1999 ◽  
Vol 121 (3) ◽  
pp. 334-343 ◽  
Author(s):  
S. Kaneko ◽  
M. Ishikawa
Keyword(s):  
Analytical Model ◽  
Wave Theory ◽  
Damping Factor ◽  
Tuned Liquid Damper ◽  
Liquid Motion ◽  
Tuned Mass Dampers ◽  
Dissipation Energy ◽  
Structure Interaction ◽  
Cable Stayed Bridge ◽  
Optimal Damping

An analytical model for describing the effectiveness of tuned liquid damper (TLD) with submerged nets for suppressing horizontal vibration of structures is proposed. Dissipation energy due to the liquid motion under sinusoidal excitation is calculated based on nonlinear shallow water wave theory. In particular, the effects of hydraulic resistance produced by nets installed in a tank on the performance of TLDs are examined. The results of dissipation energy theoretically obtained are confirmed by experiments. To show the effectiveness of the proposed analytical model for TLD-structure interaction problems, the case in which TLD with nets is installed on top of a pylon of a cable-stayed bridge is described and the calculated results are compared with the actual experimental data. In the calculation, it is shown that the optimal damping factor, as is the case for tuned mass dampers (TMD), can be produced by the nets, and the effectiveness of TLD with nets are demonstrated.

scholarly journals The production of waves by the sudden release of a spherical distribution of compressed air in the atmosphere

1941 ◽  
Vol 178 (973) ◽  
pp. 153-170 ◽  
Keyword(s):  
Shock Wave ◽  
Sound Wave ◽  
Complete Solution ◽  
Spherical Wave ◽  
Three Dimensional ◽  
Wave Theory ◽  
Initial Distribution ◽  
Finite Amplitude ◽  
Compressed Air ◽  
Compressible Medium

An attempt has been made to develop a method for dealing with solutions of problems connected with the production of waves by spherical concentrations of compressed air. Starting from the general equations for three-dimensional spherically symmetrical flow in a homogeneous compressible medium having constant entropy everywhere, a process has been devised to apply step-by-step calculations over small intervals of time to investigate the general features of such a motion. A complete solution has been worked out in one particular case for a not very intense initial distribution of pressure, and various indirect checks have indicated that the results are reasonably accurate. These results show m any features of definite interest. As distinct from plane or spherical sound wave theory, it is found that a train of waves passes away from the centre of disturbance, the amplitudes and wave lengths falling off from wave to wave. Furthermore, as distinct from finite amplitude plane wave theory which shows that any wave must eventually become a shock wave, the waves obtained in the finite amplitude spherical wave case show no indication of becoming shock waves, and indeed show towards the closing stages of the calculation a similarity to sound wave propagation. The method is applicable to any spherically symmetrical motion up to such a time as the formation of a shock wave takes place and then fails owing to the assumption of constant entropy.

scholarly journals Gas Response to a Rotating Stellar Bar

1978 ◽  
Vol 3 (3) ◽  
pp. 234-236
Author(s):  
M. P. Schwarz
Keyword(s):  
Spiral Galaxies ◽  
Fast Rate ◽  
Density Wave ◽  
Wave Theory ◽  
Finite Amplitude ◽  
Spiral Waves ◽  
Galactic Rotation ◽  
Spiral Pattern ◽  
Density Wave Theory ◽  
Gas Response

The arms in spiral galaxies cannot be material arms for then they would wind up on a time scale of one galactic rotation, or a few times 108 years. The large number of spirals suggests that the spiral pattern must persist for about 1010 years (or be continually rejuvenated). The density wave theory treats the spiral pattern as a wave phenomenon, thus overcoming this problem. Much work has been done studying small amplitude oscillations in flat stellar discs. Self-consistent spiral modes have been found, but they are not stable and grow at a fast rate. Numerical simulations of thin stellar discs, such as those of Hohl (1971), which can handle finite amplitude waves, have been more successful. Spiral waves form initially but evolve into a steady state rotating bar. It seems therefore, that a long-lived spiral cannot be formed in stars alone.

Investigations on Coherence of Active Control of Traffic Noise Transmission through an Open Window into a Rectangular Room in High-Rise Buildings

2003 ◽  
Vol 34 (8) ◽  
pp. 8-17
Author(s):  
Jiping Zhang
Keyword(s):  
Traffic Noise ◽  
Active Noise Control ◽  
Low Frequency ◽  
Wave Theory ◽  
High Rise ◽  
High Rise Building ◽  
Frequency Components ◽  
Open Window ◽  
Rectangular Room ◽  
Good Agreement

A method for theoretically calculating the coherence between sound pressure inside a rectangular room in a high-rise building and that outside the open window of the room is proposed. The traffic noise transmitted into a room is generally dominated by low-frequency components, to which active noise control (ANC) technology may find an application. However, good coherence between reference and error signals is essential for effective noise reduction and should be checked first. Based on traffic noise prediction methods, wave theory, and mode coupling theory, the results of this paper enable one to determine the potentials and limitations of ANC used to reduce such a transmission. Experimental coherence results are shown for two similar, empty rectangular rooms located on the 17th and 30th floors of a 34 floor high-rise building. The calculated results with the proposed method are generally in good agreement with the experimental results and demonstrate the usefulness of the method for predicting the coherence.

scholarly journals Numerical Simulation Analysis and Experimental Research on Damping Performance of a Novel Magnetic Fluid Damper

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Wenrong Yang ◽  
Dejie Wei ◽  
Jianzheng Su ◽  
Xiaorui Yang ◽  
Qingxin Yang
Keyword(s):  
Magnetic Field ◽  
Magnetic Fluid ◽  
Simulation Analysis ◽  
Damping Ratio ◽  
Low Frequency ◽  
Operating Characteristics ◽  
Damping Force ◽  
Rolling Ball ◽  
High Rise ◽  
Field Coupling

Considering the low-frequency and large-amplitude vibration characteristics of the high-rise structure, a tuned magnetic fluid rolling-ball damper is proposed to suppress the vibration of the structure. By adjusting the external magnetic field to control the natural rolling frequency of the ball, the purpose of tuning vibration reduction is achieved. Firstly, the working principle of the damper is theoretically analysed, a three-dimensional (3D) magnetic-fluid-solid multiphysical field coupling mathematical model of the damper is established and the governing equations of multiphysical field coupling are derived. Secondly, the magnetic field distribution and operating characteristics of the damper are simulated and analysed. Finally, the effectiveness of the model is verified by experiments, and the damping performance of the damper with two kinds of magnetic fluid is tested and compared. The results show that the magnetic-fluid-solid multiphysical field coupling model can accurately simulate the working characteristics of the damper. The maximum damping force of the damper is about 12% of the elastic force of the structure, which can increase the damping ratio of the structure by about two times, effectively reduce the vibration response time, and suppress the vibration of the high-rise structure.

scholarly journals Numerical Simulation of Cavitation and Damping Force Characteristics for a High-Speed Supercavitation Vehicle

2021 ◽  
Vol 9 (11) ◽  
pp. 1171
Author(s):  
Rui Lu ◽  
Guang Pan ◽  
Kun Tan ◽  
Shaoping Yin
Keyword(s):  
High Speed ◽  
Flow Model ◽  
Hydrodynamic Force ◽  
Angle Of Attack ◽  
Navier Stokes ◽  
Hydrodynamic Characteristics ◽  
Damping Force ◽  
Force Amplitude ◽  
Wet Surface ◽  
Force Characteristics

In this study, an attempt has been made to investigate the supercavitation and hydrodynamic characteristics of high-speed vehicles. A homogeneous equilibrium flow model and a Schnerr–Sauer model based on the Reynolds-averaged Navier–Stokes method are used. Grid-independent inspection and comparison with experimental data in the literature have been carried out to verify the accuracy of numerical methods. The effect of the navigation speed and angle of attack on the cavitation morphology and dynamic characteristics has been investigated. It has been demonstrated that the angle of attack has a remarkable influence on the wet surface and hydrodynamic force, whereas navigation speed has little effect on the position force of the vehicle under the circumstance of no wet surface. The hydrodynamic force changes periodically with the swing of the vehicle, but its maximum is greater than that for the direct navigation state at the same attack angle. Moreover, the damping effect obviously affects the hydrodynamic force amplitude and movement trend.

scholarly journals THE EFFECT OF ROUGHNESS ON THE MASS-TRANSPORT OF PROGRESSIVE GRAVITY WAVES

1966 ◽  
Vol 1 (10) ◽  
pp. 11 ◽  
Author(s):  
Arthur Brebner ◽  
J.A. Askew ◽  
S.W. Law
Keyword(s):  
Mass Transport ◽  
Gravity Waves ◽  
Orbital Motion ◽  
Wave Length ◽  
Wave Theory ◽  
Finite Amplitude ◽  
Maximum Value ◽  
Transport Velocity ◽  
Mass Transport Velocity ◽  
The Mean

On the basis of non-viscous small amplitude firstorder theory the maximum value of the horizontal orbital motion at the bed in water of constant depth his given by /U/n yy* »* " r •»** */i where k = /L, H is the wave height crest to trough, T is the period, and L the wave length (L = Sry2jr Arf 2*%/L ). On the basis of finite amplitude wave theory where the particle orbits are not closed ana by the insertion of the viscous laminar boundary layer (the conducti6n solution) the mean drift velocity or mass transport velocity on a perfectly smooth bed is given by Longuet- Higgins (1952) as 7, K H* kcr where

scholarly journals HORIZONTAL WATER PARTICLE VELOCITY OF FINITE AMPLITUDE WAVES

1970 ◽  
Vol 1 (12) ◽  
pp. 19 ◽  
Author(s):  
Yuichi Iwagaki ◽  
Tetsuo Sakai
Keyword(s):  
Particle Velocity ◽  
Wave Length ◽  
Wave Theory ◽  
Approximate Expression ◽  
Finite Amplitude ◽  
Stokes Wave ◽  
Wave Crest ◽  
Amplitude Wave ◽  
Water Particle ◽  
Hot Film

This paper firstly describes two methods to measure vertical distribution and time variation of horizontal water particle velocity induced "by surface waves in a wave tank These two methods consist of tracing hydrogen bubbles and using hot film anemometers, respectively Secondly, the experimental results by the two methods are presented with the theoretical curves derived from the small amplitude wave theory, Stokes wave theory of 3rd order, and the hyperbolic wave theory as an approximate expression of the cnoidal wave theory Finally, based on the comparison of the experimental data with the theoretical curves, the applicability of the finite amplitude wave theories, which has been studied for the wave profile, wave velocity, wave length and wave crest height, is discussed from view point of the water particle velocity.

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