Dynamics of Plane Waves in a Semi-Bounded Electro-Magneto-Elastic Medium

2020 ◽  
Vol 992 ◽  
pp. 934-939
Author(s):  
M.O. Levi
Keyword(s):  
Elastic Medium ◽  
Plane Waves ◽  
Surface Boundary ◽  
Harmonic Oscillations ◽  
Mechanical Coupling ◽  
Phase Velocities ◽  
Surface Boundary Conditions ◽  
Load Vector ◽  
Electrical Induction ◽  
The Magnetic Field

The problem of harmonic oscillations in electro-electromagnetic composites is studied. Oscillations can be initiated by the extended load vector, including the horizontal and vertical components of mechanical displacements, and electrical induction distributed on top of the surface. Boundary conditions assume full mechanical coupling for all layers of the structure. Electrical conditions on the surface top can be both electrically open, and electrically shorted. Magnetic conditions are similar to electric ones and describe the continuity of fields in between two mediums, or indicate the isolation of the magnetic field between them. The Green's function of electro–magneto–elastic medium is constructed. Phase velocities are obtained for various geometric proportions and materials.

Reflection of inhomogeneous plane waves at the surface of a thermo-poroelastic medium

2020 ◽  
Vol 224 (3) ◽  
pp. 1621-1639
Author(s):  
Enjiang Wang ◽  
José M Carcione ◽  
Yang Yuan ◽  
Jing Ba
Keyword(s):  
Plane Waves ◽  
Thermal Relaxation ◽  
Grazing Incidence ◽  
Surface Boundary ◽  
Poroelastic Medium ◽  
Low Frequencies ◽  
Surface Boundary Conditions ◽  
Plane Wave Incident ◽  
Inhomogeneous Plane ◽  
Significant Interference

SUMMARY We analyse the reflection coefficient of an inhomogeneous plane wave incident on the thermally insulated surface of a thermo-poroelastic medium. The theory, which includes the classic Lord-Shulman (LS) and Green-Lindsay (GL) theories as well as a generalization of the LS model, predicts three inhomogeneous longitudinal waves and one transverse wave, described by potential functions specified by the propagation direction and inhomogeneity angle. The GL model can give a stronger P1-wave thermal attenuation and consequently a stronger velocity dispersion than the LS model. We investigate the influence of inhomogeneity angle, type of incident wave, frequency and surface boundary conditions. The generalized LS model exhibits increased P1-wave thermal attenuation with increasing Maxwell–Vernotte–Cattaneo relaxation time and consequently predicts more interference energy, irrespective if the surface is open or sealed. The inhomogeneity angle affects the energy partitions particularly near the grazing incidence, with a significant interference energy, which must be taken into account to satisfy the energy conservation. The thermal dispersion occurs at frequencies around the thermal relaxation peak, which moves to low frequencies when the conductivity increases.

Modeling Active Layer Depth of Permafrost Changing Surface Boundary Conditions

2020 ◽  
Author(s):  
MODI ZHU ◽  
Jingfeng Wang ◽  
Husayn Sharif ◽  
Valeriy Ivanov ◽  
Aleksey Sheshukov
Keyword(s):  
Boundary Conditions ◽  
Active Layer ◽  
Surface Boundary ◽  
Layer Depth ◽  
Surface Boundary Conditions

scholarly journals Energy Pile Field Simulation in Large Buildings: Validation of Surface Boundary Assumptions

2019 ◽  
Author(s):  
Andrea Ferrantelli ◽  
Jevgeni Fadejev ◽  
Jarek Kurnitski
Keyword(s):  
Boundary Conditions ◽  
Single Point ◽  
Ground Surface ◽  
Thermal Mass ◽  
Heat Equations ◽  
Outlet Temperature ◽  
Surface Boundary ◽  
Geothermal Heat ◽  
Soil Medium ◽  
Surface Boundary Conditions

As the energy efficiency demands for future buildings become increasingly stringent, preliminary assessments of energy consumption are mandatory. These are possible only through numerical simulations, whose reliability crucially depends on boundary conditions. We therefore investigate their role in numerical estimates for the usage of geothermal energy, performing annual simulations of transient heat transfer for a building employing a geothermal heat pump plant and energy piles. Starting from actual measurements, we solve the heat equations in 2D and 3D using COMSOL Multiphysics and IDA-ICE, and discover a negligible impact of the multiregional ground surface boundary conditions. Moreover, we verify that the thermal mass of the soil medium induces a small vertical temperature gradient on the piles surface. We also find a roughly constant temperature on each horizontal cross-section, with nearly identical values if the average temperature is integrated over the full plane or evaluated at one single point. Calculating the yearly heating need for an entire building we then show that the chosen upper boundary condition affects the energy balance dramatically. Using directly the pipes’ outlet temperature induces a 54% overestimation of the heat flux, while the exact ground surface temperature above the piles reduces the error to 0.03%.

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