Plane waves in a semi-infinite fluid saturated porous medium

The field equations governing the propagation of waves in an incompressible liquid-saturated porous medium are investigated and a general solution is presented. It has been revealed that coupled longitudinal and transverse waves propagate in the porous medium. The propagation of transverse waves in the fluid phase is completely due to the interaction between the solid and fluid phases. The dispersion relationship and attenuation features are discussed. Unlike other investigations, all explicit forms of the arguments are derived. The reflection of the plane harmonic waves at the plane, traction-free boundary, which shows the influence of the dissipation on the velocity, and the attenuation coefficients of the reflected waves is studied. It is of interest that pore pressure is produced in the process of reflection, even in the case of the incidence of transverse waves.     

Two-Phase Flow and the Capillarity Phenomenon in Porous Solids – A Continuum Thermomechanical Approach

Two-phase flow and capillarity phenomenon in porous solids, well known in physics and engineering, are treated from a rigorous continuum thermomechanical point of view for the first time. A ternary model, consisting of a porous solid phase, a liquid phase, and a gas phase, is investigated within the framework of thermodynamics. The main result of the evaluation of the entropy principle turns out to be that the interaction forces between the solid, gas, and liquid phases are dependent on the free Helmholtz energy functions of the corresponding phases and on the gradient of the liquid density. The classical result for the driving volume force for raising a water column in a narrow tube against the force of gravity is contained in the general investigation.     

Zur Theorie der viskoplastischen Stoffe

Zusammenfassung Für viskoplastische Stoffe wird eine modifizierte Stoffgleichung der bekannten Ansätze von Perzyna [1] vorgeschlagen. Mit dieser Stoffgleichung gelingt es bei relativ langsam viskoplastischem Fließen die Eindeutigkeit der Lösungen nachzuweisen und zwei Extremalprinzipe anzugeben, die es gestatten, den wirklichen Spannungs- und Verzerrungsgeschwindigkeitszustand einzuschränken.

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Summary A modified form of the well-known equations from Perzyna [1] for viscoplastic material is presented. With these modified equations, one can prove the uniqueness of the solution and derive extremum principles for the problems having slow viscoplastic flow. Using these extremum principles, the upper and lower bounds for the actual stresses and the rate of change of strains can be given.

     

Saturated Elastic Porous Solids: Incompressible,Compressible and Hybrid Binary Models

Constitutive models for a general binary elastic-porous media are investigated by two complementary approaches. These models include both constituents treated as compressible/incompressible, a compressible solid phase with an incompressible fluid phase (hybrid model of first type), and an incompressible solid phase with a compressible fluid phase (hybrid model of second type). The macroscopic continuum mechanical approach uses evaluation of entropy inequality with the saturation condition always considered as a constraint. This constraint leads to an interface pressure acting in both constituents. Two constitutive equations for the interface pressure, one for each phase, are identified, thus closing the set of field equations. The micromechanical approach shows that the results of Didwania and de Boer can be easily extended to general binary porous media.     

Saturated Compressible and Incompressible Porous Solids: Macro- and Micromechanical Approaches

In this paper two complementary approaches are used to describe the mechanical behavior of saturated compressible and incompressible porous solids. The macroscopic investigation is based on the mixture theory, restricted by the volume fraction concept. In the micromechanical approach, a hierarchy of conditionally ensemble averaged fluid and solid phase momentum balance equations are derived for a simple model of quasi-static liquid saturated porous media. The ensemble averaged equations for both the phases agree remarkably well with the macroscopic results. A micromechanical basis for Terzhagi's effective stress concept is presented. In addition, an expression for additional partial solid stress modifying the effective stress principle, to account for deformability of solid materials, is also derived.     

Vibrational spectra and force constants of symmetric tops: Rotational analysis of ν3 and 2ν3 of H3Si35Cl and H3Si37Cl

The gas-phase infrared spectra of natural and ³⁵Cl isotopically enriched H₃SiCl have been recorded with a resolution of 0.04 cm^?1 in the regions of ν₃ (～550 cm^?1) and 2ν₃ (～1100 cm^?1). The fundamentals of species with ²⁸Si, ²⁹Si, ³⁰Si, ³⁵Cl, and ³⁷Cl and several hot bands of the series nν₃ + mν_i ? mν_i (n, m = 1, 2; i = 3 and 6) have been detected. The parameters ν₀, x₃₃, x₃₆, B₀, α₃^A, D_J⁰ and D_J³ were determined by a combination of least-squares analysis of P and R branches resolved into J peaks (J ≤ 90) and a band contour simulation. Possible resonances of nν₃ and (n ? 1)ν₃ + ν₆ are discussed.     

Vibrational spectra and force constants of symmetric tops: Rovibrational spectra in the ν3 region of monoisotopic species of H3GeCl,H3GeBr,and H3GeI

The gas phase infrared spectra of several monoisotopic species of H₃GeCl, H₃GeBr, and H₃GeI have been recorded in the ν₃ region near 420, 300, and 250 cm^?1, respectively, with a resolution between 0.03 and 0.04 cm^?1. Rotational J structure of the fundamental and of several “hot” bands of ν₃ has been resolved and analyzed by means of polynomial methods. The K structure of J clusters is indicated, and α₃^A values were estimated from a band contour simulation. The molecular parameters ν₃⁰, χ₃₃, (B₃-B₀), and $\text{D}{}_{\mathrm{J}}$ were determined for several isotopic combinations. The ν₃ and 2ν₃ levels are apparently unperturbed except for H₃Ge³⁵Cl species for which Fermi resonance between 2ν₃ and ν₂ has been established.     

Fundamental Solution of the System of Equations of Steady Oscillations in the Theory of Fluid-Saturated Porous Media

In the present paper the linear theory of the liquid-saturated porous medium consisting of a microscopically incompressible solid skeleton containing microscopically incompressible liquid is considered. The fundamental solution of the system of linear coupled partial differential equations of the steady oscillations of the porous solids is constructed in terms of elementary functions and some basic properties are established.     

The Bis(pentafluoroethyl)phosphinous Acid (C2F5)2POH

Phosphinous acid or phosphane oxide? Both tautomers of (C₂F₅)₂POH (see picture) are found in the neat liquid, whereas only phosphinous acid is present in the gas phase or in solution. The synthesis starting from (C₂F₅)₃PF₂, the thermodynamics of the tautomerization, and the detection and thermodynamics of the cis‐/trans‐P? OH rotamers of the acid are described.