1,720,968 research outputs found
General analysis of discontinuity waves in thermoviscoelastic solids of integral type
No full textIn this paper we study the propagation of general discontinuity waves of order N≥1 through a homogeneous anisotropic linear thermoviscoelastic solid whose heat flux vector depends upon the past history of the temperature gradient. After determining the normal speeds of propagation we state the evolution law of the discontinuities along the rays associated with the wave front. The results are independent of N. © 1991 Società Italiana di Fisica
Alcuni risultati nella dinamica dei solidi elastici inestensibili
No full textIn this paper the Authors first formulate a very general mixed boundary-value problem for dynamics of inextensible elastic solids and they establish for this problem a theorem of uniqueness of solution in bounded and unbounded domains. Then they consider displacement boundary-value problem for which they obtain another theorem of uniqueness of solution. At last the Authors establish a reciprocal theorem for bounded and unbounded domains. © 1980 Università degli Studi di Ferrara
Stationary magnetic flow of a second grade fluid past a rotating plane: exact solutions
No full textExact solutions are given for the steady flow of
a second grade fluid occupying the halfspace S past the
plane z=0 uniformly rotating about a fixed normal axis (z-axis). No conditions on the sign of the material parameters
characterizing the second grade fluid are imposed. The solutions
are obtained in a velocity field of the form considered by Berker. Then a uniform magnetic field H_0 orthogonal to the (electrically non conducting) rotating plane is impressed. The induced magnetic field is supposed depending only on z. The results are compared with those corresponding to the
Newtonian case and some numerical simulations are given
Flow and stability of a micropolar fluid past a rotating plane
No full textAn exact solution is given for the steady flow of
a micropolar fluid occupying the halfspace past the plane z=0
uniformly rotating about a fixed normal axis (z-axis).
This solution is obtained in a velocity field of the form
considered by Berker and supposing the microrotation
depending only on z. The stability of this flow is then studied
using the energy method. The results are compared with those
corresponding to the Newtonian case and can be deduced as a
limiting case, as h tends to infinity, of the solution to the problem
relative to the strip of width h
Time-periodic Poiseuille flow in a pipe for some classes of fluids
No full textWe consider a fully developed time-periodic pipe
flow (Poiseuille flow) for some classes of fluids (micropolar
fluids, mixtures of fluids). Such physical cases lead to a
parabolic system in which the pressure gradient is a
time-periodic function with either only one non vanishing
component or the components proportional to a single time-periodic
function. For such situations we generalize the results
concerning the Newtonian case
Steady Flow of a Viscous Incompressible Fluid in an Unbounded “Funnel-Shaped” Domain
No full textexistence and asymptotic decay in space of steady motions of a viscous fluid in an unbounded domai
Exact solutions in MHD natural convection of a Bingham fluid: fully developed flow in a vertical channel
No full textIn nature, many fluid-like materials exhibit a yield stress below which they behave like a solid. The Bingham model aims to describe such materials. This paper draws some mathematical considerations on the flow of a Bingham fluid in a vertical channel. The situation due to the presence of an external magnetic field and natural convection is analyzed: the external magnetic field, which is orthogonal to the walls of the channel, generates the Lorentz forces that influence the motion through the Hartmann number. The behavior of the velocity, the induced magnetic field and the thickness of the plug regions are discussed and presented graphically. We find that the velocity is a decreasing function of the Bingham and Hartmann numbers. In particular, the presence of the external magnetic field increases the thickness of the plug region. The modulus of the induced magnetic field is not monotone when the Hartmann number changes, but it is a decreasing function of the Bingham number
Mixed Magnetoconvection of Nanofluids in a Long Vertical Porous Channel
No full textThis paper aimed to study the flow of a nanofluid in a long vertical porous channel when an external uniform magnetic field is impressed. The Buongiorno two-phase model of nanofluid is supposed to be slightly compressible in order to assume the Oberbeck-Boussinesq approximation. The velocity, the induced magnetic field, the temperature, and the nanoparticle volume fraction are analytically obtained. Detailed considerations are drawn for the occurrence of the reverse flow phenomenon. Moreover, a selected set of plots illustrating the influence of various parameters involved in the problem is presented and discussed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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