Wyniki wyszukiwania - BazTech

1

Thermodynamics analysis of an MHD casson fluid flow through a rotating permeable channel with slip and hall effects

Eegunjobi Adetayo Samuel, Makinde Oluwole Daniel

Engineering Transactions

|

2020

|

Vol. 68, iss. 3

239--252

EN

In this paper, the inherent irreversibility in a Casson fluid flow through a rotating permeable microchannel with wall slip and Hall current is investigated. It is assumed that the lower wall is subjected to the velocity slip and fluid injection while the fluid suction occurs at the upper wall. The nonlinear governing equations of momentum and energy balance are obtained, analyzed and solved numerically using the shooting technique together with the Runge-Kutta-Fehlberg integration method. Pertinent results depicting the effects of various embedded thermophysical parameters on the fluid velocity, temperature, skin friction, the Nusselt number, entropy generation rate and the Bejan number are presented graphically and discussed. It is found that the entropy generation rate is enhanced by fluid rotation and velocity slip but lessened with a rise magnetic field intensity. Our results will undoubtedly augment the design and efficient operation of micro-cooling devices, micro-heat exchangers, micropumps and micro-mixing technologies.

2

Hall effects on unsteady MHD flow between two disks with non-coincident parallel axes of rotation

Das S., Maji M., Guria M., Jana R. N.

International Journal of Applied Mechanics and Engineering

|

2010

|

Vol. 15, no 1

5-18

EN

Hall effects on the unsteady MHD flow of a viscous incompressible electrically conducting fluid between two disks with reference to non-coaxial parallel axes of rotation have been studied. It is rigorously stated that there arises an axisymmetric solution of this problem as referred to a rigid body rotation. An exact solution of the governing equation has been obtained by applying the Laplace transform technique. It is found that the torque experienced by the disks decreases with an increase in the Hall parameter, m.

3

Influence of the magnetic field on the charge transport in InxGa1-xAs (0 x ≤ x ≤ 1) MBE layers

Wolkenberg A., Przesławski T.

Elektronika : konstrukcje, technologie, zastosowania

|

2008

|

Vol. 49, nr 2

72-75

EN

The Hali effect and magnetoresistance measurements in InxGa1-xAs alloys have been carried out over the entire range of compositions x(x=0, x=0.53 and x=1) in the magnetic field up to 1.5 T. InGaAs layers were grown by molecular beam epitaxy (MBE) onto GaAs and InP substrates. Despite the large lattice mismatch (≤ 7.2%) InxGa1-xAs layers showed excellent morphological and structural properties as determined by double crystal X-ray diffraction. Heteroepitaxially grown InAs and In0.53Ga0.47As layers exhibited pronounced maximum of Hali coefficient at temperaturę about ~60 K, which is characteristic of impurity-band transport. Additionally all InGaAs layers showed several anomalous behaviour like strong non-linear character in the magnetic field dependence of their Hali coefficients, non-quadratic weak magnetic field dependence of magnetoresistance, and the temperature dependence of their electron mobility. These are attributed to inhomogeneous distribution of misfit dislocation, and are interpreted in terms of two-layer model, one with bulk like and the other with strongly dislocated region at the heterointerface.

PL

Pomierzono zjawisko Halla i magnetorezystancje w stopach InxGa1-xAs przy różnych wartościach x (x = 0, x=0,53 i x= 1) w polach magnetycznych do 1,5 T. Warstwy InGaAs były osadzane na podłożach z GaAs i InP w procesie MBE. Pomimo dużego niedopasowania sieciowego (≤ 7,2%) warstwy InxGa1-xAs wykazują dobrą strukturę, co wynika z badań XRD. Heteroepitaksjalne warstwy InAs i In0.53Ga0.47As wykazują się maksimum współczynnika Halla w temperaturze ~60 K charakterystyczną dla transportu przez pasmo domieszek. Ponadto warstwy InGaAs wykazują silnie nieliniowy charakter zależności współczynnika Halla od pola magnetycznego, niewielkie odchylenie od zależności kwadratowej magnetorezystancji od pola magnetycznego i zależność temperaturową ruchliwości elektronów. Przypisujemy to niehomogenicznemu rozkładowi dyslokacji niedopasowania i interpretujemy to w modelu dwuwarstwowym, składającym się z warstwy obszaru objętościowego i warstwy międzypowierzchniowej przy podłożu, silnie wzbogaconej dyslokacjami.

4

Hall effects on MHD low and heat transfer over a stretching surface

Gupta A. S., Pal A., Pal B., Takhar H. S.

International Journal of Applied Mechanics and Engineering

|

2003

|

Vol. 8, no 2

219-232

EN

A magnetohydrodynamic (MHD) flow of an incompressible viscous electrically conducting fluid over a stretching surface is investigated when the fluid is permeated by a uniform transverse magnetic field and Hall effects are taken into account. It is found that for a flow at small magnetic Reynolds number past the surface which is stretched with a velocity proportional to the distance from a fixed point, velocity profiles are similar. For a fixed value of the Hall parameter m, components of velocity along and normal to the surface at a given point decrease with an increase in the magnetic parameter M. However for fixed values of m and M, the cross-flow velocity component induced by Hall currents reaches a maximum value at a certain height from the surface and the profiles for this velocity component shift towards the left with an increase in M. A novel result of the analysis is that for a fixed value of M, the primary velocity component remains positive for small values of the Hall parameter (m=<0.5) and becomes negative for m>0.5 indicating flow reversal. The region of this flow reversal increases with an increase in m. A similarity solution for temperature distribution in the above flow is also found and the rate of heat transfer at the stretching surface is computed for various values of m and M.