1,190 research outputs found
MHD oblique stagnation-point flow of a Newtonian fluid
No full textThe steady two-dimensional oblique stagnation-point flow of
an electrically conducting Newtonian fluid in the presence of a uniform
external electromagnetic field (E0,
H0) is analyzed, and some physical
situations are examined. In particular, if E0 vanishes, H0 lies in the
plane of the flow, with a direction not parallel to the boundary, and
the induced magnetic field is neglected, it is proved that the oblique
stagnation-point flow exists if, and only if, the external magnetic field
is parallel to the dividing streamline. In all cases it is shown that the
governing nonlinear partial differential equations admit similarity solutions, and the resulting ordinary differential problems are solved numerically. Finally, the behaviour of the flow near the boundary is analyzed;
this depends on the Hartmann number if H0 is parallel to the dividing
streamline
MHD OBLIQUE STAGNATION-POINT FLOW OF A MICROPOLAR FLUID
No full textThe steady two-dimensional oblique stagnation-point flow of an electrically
conducting micropolar fluid in the presence of a uniform external electromagnetic field
(E0,H0) is analyzed and some physical situations are examined. In particular, if E0
vanishes, H0 lies in the plane of the flow, with a direction not parallel to the boundary,
and the induced magnetic field is neglected. It is proved that the oblique stagnationpoint
flow exists if, and only if, the external magnetic field is parallel to the dividing
streamline. In all cases it is shown that the governing nonlinear partial differential
equations admit similarity solutions and the resulting ordinary differential problems are
solved numerically. Finally, the behaviour of the flow near the boundary is analyzed;
this depends on the three dimensionless material parameters, and also on the Hartmann
number if H0 is parallel to the dividing streamline
Strain-dependent internal parameters in hyperelastic biological materials
No full textThe behavior of hyperelastic energies depending on an internal parameter, which is a function of the deformation gradient, is discussed. As an example, the analysis of two models where the parameter describes the activation of a tetanized skeletal muscle tissue is presented. In those models, the activation parameter depends on the strain and it is shown the importance of considering the derivative of the parameter with respect to the strain in order to capture the proper stress–strain relations
MHD stagnation-point flow
No full textThe flow near a stagnation-point is a fundamental topic in fluid dynamics and it has
been studied by several researches during the past decades because of its relevant
applications.
In this Thesis we investigate the influence of the electromagnetic field on the
stagnation-point flow of a Newtonian or a micropolar fluid. To this end we consider
three types of such a motion: plane orthogonal, plane oblique and three-dimensional.
We take into consideration a fluid which moves towards a flat surface.
We descrive several situations which are relevant from a physical point of view when
an external uniform or not uniform electromagnetic field is impressed.
Actually, we have prove that if the external magnetic field is uniform and the induced
magnetic field is neglected, then the stagnation-point flow exists if, and only, if
the external magnetic field has some suitable directions. Further, we compute the
induced magnetic field in the other cases.
We prove also that if the external magnetic field is not uniform and it is parallel to
the velocity at infinity then the three-dimensional stagnation-point flow is possible
if and only if it is axisymmetric.
In all the cases here considered, the MHD PDEs which govern the motion are
reduced to a system of nonlinear ODEs. These boundary values problems are then
integrated numerically and some graphics and tables are furnished in order to show
the behaviour of the solution near the obstacle
Effect of temperature on the MHD stagnation-point flow past an isothermal plate for a Boussinesquian Newtonian and micropolar fluid
No full textPurpose: This paper aims to analyze the steady two-dimensional stagnation-point flow of an electrically conducting Newtonian or micropolar fluid when the obstacle is uniformly heated. Design/methodology/approach: The governing boundary layer equations are transformed into a system of ordinary differential equations using appropriate similarity transformations. Some analytical considerations about existence and uniqueness of the solution are obtained. The system is then solved numerically using the bvp4c function in MATLAB. Findings: If the temperature of the obstacle Tw coincides with the environment temperature T0, then the motion reduces to the usual orthogonal stagnation-point flow; if Tw = T0, then it is necessary to include in the similarity function describing the velocity an oblique part due to the temperature. Also, the presence of a uniform external magnetic field orthogonal to the obstacle is examined. In all cases, the motion is reduced to a system of nonlinear ordinary differential equations with boundary conditions, whose solution is discussed numerically when the Prandtl and the Hartmann number varies. Originality/value: The present results are original and new for the problem of magnetohydrodynamic mixed convection in the plane stagnation-point flow of a Newtonian or a micropolar fluid over a vertical flat plate. At infinity, the motion approaches the orthogonal stagnation-point flow of an inviscid fluid; the effect of an uniform external magnetic field is considered, and the obstacle has a uniform temperature
Esame di Stato 2016: Matematica
No full textViene proposta una possibile soluzione del tema di Matematica relativo alla seconda prova dell’Esame di Stato 2016 per il Liceo Scientifico. Nella risoluzione alcuni semplici calcoli sono lasciati al lettore, per non appesantire troppo l’esposizione. A seguire viene dato un commento personale sulla prova
THREE-DIMENSIONAL MHD STAGNATION POINT FLOW OF A NEWTONIAN AND A MICROPOLAR FLUID
No full textThe steady three-dimensional stagnation-point flow of an electrically conducting Newtonian or micropolar fluid in the presence of a uniform external magnetic field {\H}_0 is analysed and some physical situations are examined.
In particular, we prove that, if we impress an external magnetic field {\H}_{0}, and we neglect the induced magnetic field, then the steady three-dimensional MHD stagnation-point flow is possible if, and only if, {\H}_0 has the direction of one of the coordinate axes.
In all cases it is shown that the governing nonlinear partial differential equations admit similarity solutions. We find that the flow has to satisfy an ordinary differential problem whose solution depends on {\H}_{0} through the Hartmann number .
Finally, the skin-friction components along the axes are computed
Magnetohydrodynamic Flow of a Bingham Fluid in a Vertical Channel: Mixed Convection
No full textIn this paper, we describe our study of the mixed convection of a Boussinesquian Bingham
fluid in a vertical channel in the absence and presence of an external uniform magnetic field normal to
the walls. The velocity, the induced magnetic field, and the temperature are analytically obtained. A
detailed analysis is conducted to determine the plug regions in relation to the values of the Bingham
number, the buoyancy parameter, and the Hartmann number. In particular, the velocity decreases
as the Bingham number increases. Detailed considerations are drawn for the occurrence of the
reverse flow phenomenon. Moreover, a selected set of diagrams illustrating the influence of various
parameters involved in the problem is presented and discussed
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
Numerical simulations of three-dimensional MHD stagnation-point flow of a micropolar fluid
No full textIn this paper the steady three-dimensional stagnation-point flow of an incompressible, homogeneous, electrically conducting micropolar fluid over a flat plate is numerically investigated. The fluid is permeated by a uniform external magnetic field H0. The effects of the magnetic field on the velocity and on the microrotation profiles are presented graphically and discussed. The results obtained indicate that the thickness of the boundary layer decreases when the magnetic field increases. Moreover H0 tends to prevent the occurrence of the reverse flow and of the reverse microrotation
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