Wave attenuation prediction through a volume of random located lossy-dielectric branches — 3-D vector transport theory

2012 ◽  
Author(s):  
Saul A. Torrico ◽  
Roger H. Lang
Keyword(s):  
Transport Theory ◽  
Wave Attenuation ◽  
Vector Transport ◽  
Lossy Dielectric

Electromagnetic Wave Attenuation in Lossy Dielectric

2015 ◽  
Vol 815 ◽  
pp. 198-202 ◽  
Author(s):  
Ade Anis Afrizal ◽  
Nurul Khadiko ◽  
Fitria Gani Sulistya ◽  
Vita Nur Septyani ◽  
H. Ahmad Lubis
Keyword(s):  
Electromagnetic Wave ◽  
Wave Attenuation ◽  
Electromagnetic Energy ◽  
Electromagnetic Propagation ◽  
Attenuation Value ◽  
Lossy Dielectric ◽  
Constitutive Parameters

The importance of knowing dielectric value on a medium is to perceive the capability of conducting electromagnetic wave. Most of failure on electromagnetic instruments, were due to an inaccuracy of selecting material. Improper usage of materials may cause the attenuation of electromagnetic energy. So, it is important to measure the attenuation value. In this study, we compared the attenuation value on three media such as clay, silicon and wood. The problem mentioned above, could resolved by applying the electromagnetic propagation formula using skylab program. In this study we compared the effect constitutive parameters to the attenuation value and frequency in three media. The result shows, among three materials, at the same frequency we obtain that electromagnetic energy much easily attenuated on clay compared to other materials followed by silicon and wood. The reason is due to the conductivity value. In this study, we obtain that clay is the most sensitive on attenuation value on frequency followed by silicon and wood.

THE ANALYSIS OF ULTRASONIC WAVE ATTENUATION SPECTRA IN STEELS

1983 ◽  
Vol 44 (C9) ◽  
pp. C9-337-C9-340 ◽  
Author(s):  
R. L. Smith ◽  
W. N. Reynolds ◽  
S. Perring
Keyword(s):  
Ultrasonic Wave ◽  
Wave Attenuation

Bulk drag coefficient of a subaquatic vegetation subjected to irregular waves: Influence of Reynolds and Keulegan-Carpenter numbers

2020 ◽  
pp. 34-42
Author(s):  
Thibault Chastel ◽  
Kevin Botten ◽  
Nathalie Durand ◽  
Nicole Goutal
Keyword(s):  
Drag Coefficient ◽  
Wave Height ◽  
Wave Attenuation ◽  
Empirical Relationship ◽  
Breaking Waves ◽  
Irregular Waves ◽  
Geometrical Parameters ◽  
Flume Experiments ◽  
Seagrass Meadows ◽  
Artificial Vegetation

Seagrass meadows are essential for protection of coastal erosion by damping wave and stabilizing the seabed. Seagrass are considered as a source of water resistance which modifies strongly the wave dynamics. As a part of EDF R & D seagrass restoration project in the Berre lagoon, we quantify the wave attenuation due to artificial vegetation distributed in a flume. Experiments have been conducted at Saint-Venant Hydraulics Laboratory wave flume (Chatou, France). We measure the wave damping with 13 resistive waves gauges along a distance L = 22.5 m for the “low” density and L = 12.15 m for the “high” density of vegetation mimics. A JONSWAP spectrum is used for the generation of irregular waves with significant wave height Hs ranging from 0.10 to 0.23 m and peak period Tp ranging from 1 to 3 s. Artificial vegetation is a model of Posidonia oceanica seagrass species represented by slightly flexible polypropylene shoots with 8 artificial leaves of 0.28 and 0.16 m height. Different hydrodynamics conditions (Hs, Tp, water depth hw) and geometrical parameters (submergence ratio α, shoot density N) have been tested to see their influence on wave attenuation. For a high submergence ratio (typically 0.7), the wave attenuation can reach 67% of the incident wave height whereas for a low submergence ratio (< 0.2) the wave attenuation is negligible. From each experiment, a bulk drag coefficient has been extracted following the energy dissipation model for irregular non-breaking waves developed by Mendez and Losada (2004). This model, based on the assumption that the energy loss over the species meadow is essentially due to the drag force, takes into account both wave and vegetation parameter. Finally, we found an empirical relationship for Cd depending on 2 dimensionless parameters: the Reynolds and Keulegan-Carpenter numbers. These relationships are compared with other similar studies.

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