1,893 research outputs found
Stability of flow of a thermoviscoelastic fluid between rotating coaxial circular cylinders
The stability problem of thermoviscoelastic fluid flow between rotating coaxial cylinders is investigated using nonlinear thermoviscoelastic constitutive equations due to Eringen and Koh. The velocity field is found to be identical with that of the classical viscous case and the case of the viscoelastic fluid, but the temperature and pressure fields are found to be different. By imposing some physically reasonable mechanical and geometrical restrictions on the flow, and by a suitable mathematical analysis, the problem is reduced to a characteristic value problem. The resulting problem is solved and stability criteria are obtained in terms of critical Taylor numbers. In general, it is found that thermoviscoelastic fluids are more stable than classical viscous fluids and viscoinelastic fluids under similar conditions
On the naturality of the Mathai-Quillen formula
We give an alternative proof for the Mathai-Quillen formula for a Thom form
using its natural behaviour with respect to fiberwise integration. We also
study this phenomenon in general context.Comment: 6 page
FEM Analysis of Gun Tank Turret
Turret of a battle tank is of complicated geometry with complex loading conditions. Finite element analysis of turret structure is carriedout by using a package program SAP IV for various loadings.Experimental analysis is carried out by strain gauge method on 115th scale model and the results are compared. The suitability of finite element method in this area of stress analysis of tank turrets to assess the design adequacy and opimisation h-comes apparent
Elastic and Chemical Contributions to the Stability of Magnetic Surface Alloys on Ru(0001)
We have used density functional theory to study the structural stability of
surface alloys. Our systems consist of a single pseudomorphic layer of
on the Ru(0001) surface, where = Fe or Co, and = Pt, Au,
Ag, Cd, or Pb. Several of the combinations studied by us display a preference
for atomically mixed configurations over phase-segregated forms. We have also
performed further {\it ab initio} calculations to obtain the parameters
describing the elastic interactions between atoms in the alloy layer, including
the effective atomic sizes at the surface. We find that while elastic
interactions favor alloying for all the systems considered by us, in some cases
chemical interactions disfavor atomic mixing. We show that a simple criterion
(analogous to the Hume-Rothery first law for bulk alloys) need not necessarily
work for strain-stabilized surface alloys, because of the presence of
additional elastic contributions to the alloy heat of formation, that will tend
to oppose phase segregation.Comment: 10 pages, 8 figures Submitted To Phys. Rev.
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