scholarly journals Influence of Second Viscosity on Pressure Pulsation

2019 ◽  
Vol 9 (24) ◽  
pp. 5444
Author(s):  
Daniel Himr ◽  
Vladimír Habán ◽  
Simona Fialová
Keyword(s):  
Pipeline System ◽  
Pressure Pulsations ◽  
Low Frequencies ◽  
Water Power ◽  
Flexible Pipes ◽  
Power Plant Control ◽  
Dependent Model ◽  
Newtonian Liquids ◽  
Frequency Dependent Model ◽  
Difficult Cases

A mathematical model of pulsating flow is proposed in the paper. The model includes more accurate description of energy dissipation, so it allows, for example, better stability analysis of water power plant control and more effective operation. Flow in a pipeline system is usually treated as a one-dimensional flow. This is also applied for more difficult cases of the Newtonian and non-Newtonian liquids simulations in the rigid or flexible pipes. Computational simulations of pressure pulsations in pipelines often predict lower damping than what the experimental results show. This discrepancy can be caused by neglecting one of the important damping mechanisms. The second viscosity describes the energy losses due to the compressibility of the liquid. Its existence and use in the computations specifies the real pulsations damping descriptions and predictions. A frequency dependent model of pressure pulsations including second viscosity is introduced. The second viscosity is determined from the system eigenvalue. The experiments were performed with water for low frequencies (from 0.1 to 1 kHz). This area is not fully covered by the current available research results.

scholarly journals A Frequency-Dependent Model for the Shape of the Fourier Amplitude Spectrum of Acceleration at High Frequencies

2020 ◽  
Vol 110 (6) ◽  
pp. 2743-2754 ◽  
Author(s):  
Annabel Haendel ◽  
John G. Anderson ◽  
Marco Pilz ◽  
Fabrice Cotton
Keyword(s):  
Frequency Dependence ◽  
Amplitude Spectrum ◽  
Frequency Interval ◽  
Borehole Data ◽  
High Frequencies ◽  
Dependent Model ◽  
Fourier Amplitude Spectrum ◽  
Log Linear ◽  
Frequency Dependent Model ◽  
Quality Factor Q

ABSTRACT The high-frequency decay term of the acceleration spectrum κ is a commonly used parameter in engineering seismology. In recent years, the assumption of a linearly decaying spectrum in log–linear space has been recognized to not always be valid as the value of κ depends on the analyzed frequency band. We present an alternative model for the spectral falloff in which the frequency dependence is explicitly taken into account. This is motivated by observations that the quality factor Q has a power-law dependence on frequency at high frequencies. The new model describes the spectral decay with the help of two variables, opposite to the single parameter κ. The approach is applied to borehole data of the EUROSEISTEST site in Greece. The misfit between modeled and observed spectra is reduced with the new approach compared with the classical kappa model. The new estimates compare well with κ estimates if the same frequency interval is considered but additionally allows for the capture of the frequency dependence of the spectral shape.

Nonlinear Frequency-Dependent Model for Microinductors With Magnetic Core

2013 ◽  
Vol 34 (2) ◽  
pp. 304-306 ◽  
Author(s):  
Steven Gaskill ◽  
Andrei Papou ◽  
Anuraag Mohan ◽  
William French ◽  
Andreas Weisshaar
Keyword(s):  
Magnetic Core ◽  
Nonlinear Frequency ◽  
Frequency Dependent ◽  
Dependent Model ◽  
Frequency Dependent Model

scholarly journals Time- and frequency-dependent model of time-resolved coherent anti-Stokes Raman scattering (CARS) with a picosecond-duration probe pulse

2014 ◽  
Vol 140 (2) ◽  
pp. 024316 ◽  
Author(s):  
Hans U. Stauffer ◽  
Joseph D. Miller ◽  
Mikhail N. Slipchenko ◽  
Terrence R. Meyer ◽  
Benjamin D. Prince ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Probe Pulse ◽  
Frequency Dependent ◽  
Time Resolved ◽  
Dependent Model ◽  
Frequency Dependent Model ◽  
Anti Stokes

scholarly journals Steady-state flow of a shear-thinning liquid in an unbounded pipeline system

Analysis ◽  
2015 ◽  
Vol 35 (4) ◽  
Author(s):  
Giovanni P. Galdi ◽  
Carlo R. Grisanti
Keyword(s):  
Steady State ◽  
Cross Section ◽  
Existence And Uniqueness ◽  
Shear Thinning ◽  
Pipeline System ◽  
Constant Cross Section ◽  
Steady State Flow ◽  
Compactness Property ◽  
Newtonian Liquids ◽  
Steady State Solutions

AbstractWe show existence and uniqueness of steady-state solutions to the equations of generalized Newtonian liquids of shear-thinning type in an unbounded region that includes semi-infinite cylinders of constant cross-section (pipeline system). This result is established under the assumption that the datum (flow-rate) is sufficiently small. The main feature of our approach is the proof of a “global compactness” property of the sequence of approximating solutions.

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