Finite element solver for 3-D compressible viscous flows

The space shuttle main engine (SSME) has extremely complex internal flow structure. The geometry of the flow domain is three-dimensional with complicated topology. The flow is compressible, viscous, and turbulent with large gradients in flow quantities and regions of recirculations. The analysis of the flow field in SSME involves several tedious steps. One is the geometrical modeling of the particular zone of the SSME being studied. Accessing the geometry definition, digitalizing it, and developing surface interpolations suitable for an interior grid generator require considerable amount of manual labor. There are several types of grid generators available with some general-purpose finite element programs. An efficient and robust computational scheme for solving 3D Navier-Stokes equations has to be implemented. Post processing software has to be adapted to visualize and analyze the computed 3D flow field. The progress made in a project to develop software for the analysis of the flow is discussed. The technical approach to the development of the finite element scheme and the relaxation procedure are discussed. The three dimensional finite element code for the compressible Navier-Stokes equations is listed

A finite element solver for 3-D compressible viscous flows

Computation of the flow field inside a space shuttle main engine (SSME) requires the application of state of the art computational fluid dynamic (CFD) technology. Several computer codes are under development to solve 3-D flow through the hot gas manifold. Some algorithms were designed to solve the unsteady compressible Navier-Stokes equations, either by implicit or explicit factorization methods, using several hundred or thousands of time steps to reach a steady state solution. A new iterative algorithm is being developed for the solution of the implicit finite element equations without assembling global matrices. It is an efficient iteration scheme based on a modified nonlinear Gauss-Seidel iteration with symmetric sweeps. The algorithm is analyzed for a model equation and is shown to be unconditionally stable. Results from a series of test problems are presented. The finite element code was tested for couette flow, which is flow under a pressure gradient between two parallel plates in relative motion. Another problem that was solved is viscous laminar flow over a flat plate. The general 3-D finite element code was used to compute the flow in an axisymmetric turnaround duct at low Mach numbers

Geometrically nonlinear analysis of laminated elastic structures

This final technical report contains three parts: Part 1 deals with the 2-D shell theory and its element formulation and applications. Part 2 deals with the 3-D degenerated element. These two parts constitute the two major tasks that were completed under the grant. Another related topic that was initiated during the present investigation is the development of a nonlinear material model. This topic is briefly discussed in Part 3. To make each part self-contained, conclusions and references are included in each part. In the interest of brevity, the discussions presented are relatively brief. The details and additional topics are described in the references cited

Relativistic effects in neutrino-Fermi gas interactions

We study neutrino interactions in a hadron gas within a relativistic framework. The hadron matter is described by a non-interacting Fermi gas in beta equilibrium. We show that the introduction of relativistic effects causes a sizable enhancement of the neutrino-scattering cross sections.Comment: To appear in the proceedings of International School of Nuclear Physics: 27th Course: "Neutrinos in Cosmology, in Astro, Particle and Nuclear Physics". Erice, Sicily, Italy, 16-2

Hypersonic Flight and Ground Testing Activities in India

India has undertaken many hypersonic technology development programmes to meet the goals of future missions in space as well as missile development. While large scale ground based tests facilities are under construction, existing test facilities are being used to develop the preliminary design data needed for flight tests as well as for CFD code validation. A brief review of the hypersonic flight vehicle development programmes and the existing test facilities in the country along with some sample results from our laboratory for these programs is presented here

On the existence of chaotic circumferential waves in spinning disks

We use a third-order perturbation theory and Melnikov's method to prove the existence of chaos in spinning circular disks subject to a lateral point load. We show that the emergence of transverse homoclinic and heteroclinic points respectively lead to a random reversal in the traveling direction of circumferential waves and a random phase shift of magnitude $\pi$ for both forward and backward wave components. These long-term phenomena occur in imperfect low-speed disks sufficiently far from fundamental resonances.Comment: 8 pages, 5 figures, to appear in CHAOS (Volume 17, Issue 2, June 2007

A program-management plan with critical-path definition for Combustion Augmentation with Thermionic Energy Conversion (CATEC)

Thermionic energy conversion (TEC) is discussed. In recent TEC-topping analyses, overall plant efficiency (OPE) and cost of electricity (COE) improved slightly with current capabilities and substantially with fully matured technologies. Enhanced credibility derives from proven hot-corrosion protection for TEC by silicon-carbide clads in fossil fuel combustion products. Combustion augmentation with TEC (CATEC) affords minimal cost and plant perturbation, but with smaller OPE and COE improvements than more conventional topping applications. Risk minimization as well as comparative simplicity and convenience, favor CATEC for early market penetration. A program-management plan is proposed. Inputs, characteristics, outputs and capabilities are discussed

Stability Analysis For Yield And Yield Contributing Characters Of Tomato Under High Temperature Conditions

The current study was aimed at evaluating the stability of tomato yield and yield-contributing characteristics during three sowing intervals (February, March, and April) under high-temperature regimes, Pooled analysis of variance was performed on twenty-five genotypes, including eight parents, fifteen hybrids, and two checks, for seventeen agronomic traits. Except for plant height, ANOVA findings have revealed substantial differences among tomato genotypes, with environmental conditions playing a major role on genotype performance. The genotypes differed significantly in terms of days to 50% flowering, number of flowers per cluster, and fruit length, indicating significant variability among growing seasons. Furthermore, root length showed significant genotype x environment interactions, whereas the remaining variables are found non-significant. Among the three sowing intervals, February sowing (1st interval) was found to be the most beneficial environment for tomato growth, yield, and quality features, with the highest positive environmental indices for the majority of growth, yield, and quality contributing traits. In contrast, the April sowing period (3rd interval) was found to be most unfavorable, with the highest negative environmental indices for the traits studied. This study underlined the significant influence of environmental factors on the performance of tomato genotypes, in terms of multiple yield and yield-contributing attributes. The findings emphasize the importance of choosing the optimum sowing interval, with February as the most favorable season for cultivating tomatoes in the present study location under high-temperature conditions. These findings would help to guide the decision-making process in similar agro-climatic regions to improve the tomato output and quality