Catálogo de publicaciones - libros

We simulated the A1C1 liquid and found mainly dimers that are connected in the edge-sharing configuration. However, there were also other configurations such as trimers, tetramers and pentamers. The simulated data will be further analyzed to see whether the small amount of larger angles is due to the monomers or due to a small amount of corner-sharing dimers or even larger clusters such as trimer, tetramers or pentamers.

This paper is concerned with numerical considerations of viscous fluid effects on wave propagation in porous media. We apply a displacement-stress rotated staggered finite-difference (FD) grid technique to solve the elastodynamic wave equation. An accurate approximation of a Newtonian fluid is implemented in this technique by using a generalized Maxwell body. With this approach we consider the velocity predictions of the Biot theory for elastic waves in different digital rock samples. To distinguish between the low and the high frequency range we estimate the effective permeabilities by a flow simulation. Our numerical results indicate that the viscous Biot-coupling is visible in the numerical experiments. Moreover, the influences of other solid-fluid interactions (e.g. Squirt flow) are also discussed.

Compared to [33], the model of the thermal evolution of the Earth’s mantle is considerably improved. The temporal development of the radial viscosity profile due to cooling of the Earth could substantially be taken into account by numerical progress using a new variant of the temperature- and pressure-dependence of the shear viscosity of the mantle, namely Eq (5). The laterally averaged heat flow, the Urey number, the Rayleigh number and the volume-averaged temperature as a function of time come up to the expectations that stem from the parameterized evolution models. The mentioned evolution parameters of the present paper better approximate the observational data. Contrary to the parameterized curves, these quantities show temporal variations. This seems to be more realistic for geological reasons. Due to the activation enthalpy, the presented viscosity profile has a highly viscous transition layer (TL) with steep viscosity gradients at the phase boundaries. A low-viscosity zone is situated above and below the TL, each. The lithosphere moves piecewise en bloc. Thin cold sheet-like downwellings have an Earth-like distribution.

In the light of the three geoscientific satellite missions CHAMP, GRACE and GOCE the overall scientific aim is to achieve an automatism for the recovery of the Earth’s gravity field respectively the physical shape of the Earth, namely the geoid. Furthermore, an improved understanding of the spatial and temporal variations of the geoid is of great benefit for the study of the dynamics of the Earth’s lithosphere and upper mantle, global sea level variations, ocean circulation and ocean mass and heat transport, ice mass balance, the global water cycle and the interaction of these phenomena. This involves the determination of up to a hundred thousand unknown coefficients of the corresponding series expansion model from data sets which amount to several millions of observations provided by the satellites. The resulting system of equations which has to be solved for such an analysis cannot be evaluated without simplistic assumptions or within a satisfying time frame on personal computers due to hardware limitations. Consequently this challenging problem has to be tackled by means of high performance computing strategies. Only adoption of parallel programming standards such as MPI or OpenMP in conjunction with highly efficient numerical libraries allows for successfully accomplishing the demands of gravity field analysis. Indeed, the huge amount of data provided by satellite sensors, together with a high-resolution gravity field modeling, requires the determination of several ten thousands of unknown parameters and leads to the assignment that this problem is a true “challenge of calculus”.

Investigations on the spatial evolution of instabilities for hypersonic boundary-layer flows on a flat plate with dissociation are presented. A higher order compact numerical scheme allows for the detailed investigation of the linear and the non-linear evolution of the disturbance waves in the presence of chemical reactions. Compared to the ideal-gas case, lower temperatures in the boundary-layer are present. The three-dimensional disturbance behaviour is experiencing slight damping in the linear regime compared to equilibrium results. High-level disturbances can also lead to local shocklets that are treated with a hybrid ENO-scheme. Experiments for qualitative validation of the results at elevated Mach numbers are available by Mironov.

SKaMPI is now an established benchmark for MPI implementations. Two important goals of the development of version 5 of SKaMPI were the extension of the benchmark to cover more functionality of MPI, and a redesign of the benchmark llowing it to be extended more easily (thus matching requests from SKaMPI users). In the present paper we give an overview of the extension of SKaMPI-5 for the evaluation of one-sided communication and present a few selected results of benchmark runs, giving an impression of the breadth and depth of SKaMPI-5.

A look at the source code, which is available under the GPL, reveals that it was extremely easily to extend the SKaMPI with benchmarks for one-sided communication using the infrastructure of version 5.