A simple‐wave damping model for flexible marsh plants

2021 ◽  
Author(s):  
Xiaoxia Zhang ◽  
Pengzhi Lin ◽  
Heidi Nepf
Keyword(s):  
Simple Wave ◽  
Wave Damping ◽  
Damping Model

Recording of the Cavitation Phenomena when Modeling Flows in the Trunk Pipelines

2020 ◽  
pp. 7-14
Author(s):  
A.M. Sverchkov ◽  
◽  
S.I. Sumskoy ◽  
Keyword(s):  
Occupational Safety ◽  
Linear Part ◽  
Simple Wave ◽  
Pressure Profile ◽  
Real Problem ◽  
Flow Modeling ◽  
Oil Pipeline ◽  
Emergency Situations ◽  
Hydraulic Shocks ◽  
The Waves

In the article, it is proposed to use a numerical method based on the approach of S.K. Godunov to simulate boiling in a pipeline. The paper presents a statement of the real problem of modeling a water hammer, considering possible boiling of the transported liquid on a real object — an oil pipeline. When solving the problem, two variants of flow modeling when closing the valve installed at the end of the pipeline were carried out. In the first Наука и техника 14 Безопасность Труда в Промышленности • Occupational Safety in Industry • № 11'2020 • www.safety.ru case, the possibility of liquid boiling was not considered. In the second case, this opportunity was considered. The performed numerical simulation showed that in the pipeline in emergency situations, liquid columns can be formed, separated by the cavitation zones and oscillating in different phases, respectively, at the collapse of the cavitation zones, which serve as a kind of pressure dampers, the collisions of liquid columns occur, which can lead, depending on the ratio of velocities, to hydraulic shocks that occur not on the valves, but on the linear part of the pipeline (local hydraulic shocks). The waves from these collapses, interacting with each other, create the new pressure peaks that do not coincide with the pattern of simple wave circulation, which are predicted in the simulations that do not consider possible liquid boiling. As a resul t, the pressures reached in the pipeline during fluid hammer is significantly different from what it would be in the absence of boiling. When boiling is considered, the maximum reached pressures are 40 % higher. Moreover, this excess is repeated. The detailed analysis of the pressure profile in the pipeline is given in the article. Based on the results of solving this problem, it is concluded that when modeling pre–emergency and emergency situations in the pipeline, it is necessary to consider the process of possible liquid boiling, since sometimes, as in the presented case, the values of the pressure surges can be higher than the values of the pressure surges in the liquid without considering boiling, which increases the likelihood of emergency depressurization.

Tollmien--Schlichting wave damping by a streamwise oscillating Lorentz force

2008 ◽  
Vol 44 (3) ◽  
pp. 205-222 ◽  
Author(s):  
T. Albrecht ◽  
H. Metzkes ◽  
R. Grundmann ◽  
G. Mutschke ◽  
G. Gerbeth
Keyword(s):  
Lorentz Force ◽  
Wave Damping ◽  
Tollmien Schlichting

On the mechanisms of MHD wave damping in the partially ionized solar plasmas

2006 ◽  
Vol 37 (3) ◽  
pp. 447-455 ◽  
Author(s):  
M.L. Khodachenko ◽  
H.O. Rucker ◽  
R. Oliver ◽  
T.D. Arber ◽  
A. Hanslmeier
Keyword(s):  
Wave Damping ◽  
Partially Ionized ◽  
Solar Plasmas

Enhancement of wave damping for metamaterial beam structures with embedded inerter-based configurations

2021 ◽  
Vol 178 ◽  
pp. 108013
Author(s):  
Zhuang Dong ◽  
Dimitrios Chronopoulos ◽  
Jian Yang
Keyword(s):  
Wave Damping ◽  
Beam Structures

A modified damping model of vector form intrinsic finite element method for high-speed spiral bevel gear dynamic characteristics analysis

2021 ◽  
pp. 030932472110188
Author(s):  
Xiangying Hou ◽  
Yuzhe Zhang ◽  
Hong Zhang ◽  
Jian Zhang ◽  
Zhengminqing Li ◽  
...  
Keyword(s):  
Finite Element ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Numerical Solutions ◽  
Bevel Gear ◽  
Spiral Bevel Gear ◽  
Vector Form ◽  
Good Efficiency ◽  
Spiral Bevel ◽  
Damping Model

The vector form intrinsic finite element (VFIFE) method is springing up as a new numerical method in strong non-linear structural analysis for its good convergence, but has been constricted in static or transient analysis. To overwhelm its disadvantages, a new damping model was proposed: the value of damping force is proportional to relative velocity instead of absolute velocity, which could avoid inaccuracy in high-speed dynamic analysis. The accuracy and efficiency of the proposed method proved under low speed; dynamic characteristics and vibration rules have been verified under high speed. Simulation results showed that the modified VFIFE method could obtain numerical solutions with good efficiency and accuracy. Based on this modified method, high-speed vibration rules of spiral bevel gear pair under different loads have been concluded. The proposed method also provides a new way to solve high-speed rotor system dynamic problems.

scholarly journals CFD-DEM Simulation of Spouted Bed Dynamics under High Temperature with an Adhesive Model

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2276
Author(s):  
Zhao Chen ◽  
Lin Jiang ◽  
Mofan Qiu ◽  
Meng Chen ◽  
Rongzheng Liu ◽  
...  
Keyword(s):  
High Temperature ◽  
Particle Surface ◽  
Particle Collision ◽  
Gas Velocity ◽  
Spouted Bed ◽  
Dem Simulation ◽  
Linear Spring ◽  
Adhesion Model ◽  
Adhesive Model ◽  
Damping Model

Particle adhesion is of great importance to coating processes due to its effect on fluidization. Currently, Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) has become a powerful tool for the study of multiphase flows. Various contact force models have also been proposed. However, particle dynamics in high temperature will be changed with particle surface properties changing. In view of this, an adhesion model is developed based on approaching-loading-unloading-detaching idea and particle surface change under high temperature in this paper. Analyses of the adhesion model are given through two particle collision process and validated by experiment. Effects of inlet gas velocity and adhesion intensity on spouted bed dynamics are investigated. It is concluded that fluidization cycle will be accelerated by adhesion, and intensity of fluidization will be marginally enhanced by slight adhesion. Within a certain range, increasing inlet gas velocity will lead to strong intensity of particle motion. A parameter sensitivity comparison of linear spring-damping model and Hertz-Mindlin Model is given, which shows in case of small overlaps, forces calculated by both models have little distinction, diametrically opposed to that of large overlaps.

scholarly journals Optimizing the Power Take Off of a Wave Energy Converter With Regard to the Wave Climate

2005 ◽  
Vol 128 (1) ◽  
pp. 56-64 ◽  
Author(s):  
Gaelle Duclos ◽  
Aurelien Babarit ◽  
Alain H. Clément
Keyword(s):  
Wave Energy ◽  
Simple Wave ◽  
Wave Climate ◽  
Wave Energy Converter ◽  
Optimal Parameters ◽  
Energy Converter ◽  
Wave Energy Converters ◽  
Classical Wave ◽  
Project Site ◽  
Wave Conditions

Considered as a source of renewable energy, wave is a resource featuring high variability at all time scales. Furthermore wave climate also changes significantly from place to place. Wave energy converters are very often tuned to suit the more frequent significant wave period at the project site. In this paper we show that optimizing the device necessitates accounting for all possible wave conditions weighted by their annual occurrence frequency, as generally given by the classical wave climate scatter diagrams. A generic and very simple wave energy converter is considered here. It is shown how the optimal parameters can be different considering whether all wave conditions are accounted for or not, whether the device is controlled or not, whether the productive motion is limited or not. We also show how they depend on the area where the device is to be deployed, by applying the same method to three sites with very different wave climate.

A novel squeezed-film damping model for MEMS comb structures

2017 ◽  
Author(s):  
Alexandre Sinding ◽  
Arnaud Parent ◽  
Ilker E. Ocak ◽  
Wajih U. Syed ◽  
Aveek N. Chatterjee ◽  
...  
Keyword(s):  
Damping Model
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