Publication11

The present experimental investigation deals with the behaviour of a wake generated by a square cylinder developing in a curved diffuser, a curved duct, a straight duct and a straight diffuser having a same pressure gradient as in the curved diffuser. This enables a systematic study of the effects of curvature and pressure gradient on wake development. It is seen that the curvature makes the wake asymmetric; the wake half width increases on the inner side and decreases on the outer side; the inner side being the region between the centreline and the wall closer to the centre of curvature and the outer side being the region between the centreline and the other wall. It causes a higher entrainment in the inner side as compared to the outer side. An adverse pressure gradient, on the other hand, causes a higher wake growth and velocity defect but reduces the rate of decay of the velocity defect. These are not altered significantly when the curvature and pressure gradient effects are combined. The curvature enhances the Reynolds stresses and the kinetic energy on the inner side and suppresses them on the outer side which makes their profiles asymmetric. These profiles become more and more asymmetric with increase in the streamwise distance. When the effects of curvature and adverse pressure gradient are combined, the profiles become further asymmetric. © 1995 Springer-Verlag.

A suitable solid state fermentation has been developed to enhance the biological value and nutrition factor of sawdust using Pleurotus sajor-caju. Different process parameters such as temperature, pH, and substrate level have been studied. Patterns of protein production and saccharification power of the fermented mash evaluated under most suitable assay conditions were followed during the fermentation process. © 1995 Springer-Verlag.

Semi-austenitic precipitation hardened PH 15-7 Mo (Cu) stainless steel was solutionized, destabilized, and aged and TIG welded autogenously. The welds were subjected to different thermal treatments, viz., (1) directly aged, (2) destabilized and aged, (3) solutionized and destabilized and aged. Hardness survey across the weld and charpy V-notch tests were conducted on the welds. Overall, it was found that the hardness of solution treated base metal was relatively low and values varied from point to point because of the duplex structure of austenite and martensite. The toughness of the same was found to be high. As-weld metal showed similar trend.

The harmonic response of cylindrical shells with constrained damping treatment is studied by the finite element method. Two finite elements based on different kinematic hypothesis are presented and made use of in the study. Studies are carried out and results presented for shells with different core to facing thickness ratios, length to radius and boundary conditions. © 1995 Academic Press Ltd.

The role of gravitational energy in the evolution of the universe is examined. In co-moving coordinates, calculation of the Landau-Lifshitz pseudotensor for FRW models reveals that: (i) the total energy of a spatially closed universe irrespective of the equation of state of the cosmic fluid is zero at all times, (ii) the total energy enclosed within any finite volume of the spatially flat universe is zero at all times, (iii) during inflation the vacuum energy driving the accelerated expansion and ultimately responsible for the creation of matter (radiation) in the universe, is drawn from the energy of the gravitational field. In a similar fashion, certain cosmological models which abandon adiabaticity by allowing for particle creation, use the gravitational energy directly as an energy source. © 1995 Plenum Publishing Corporation.