The EPR investigations of Cu2+ doped K2Zn(SO4)2.6(H2O) and (NH4)2Zn(SO4)2.6(H2O) Tutton salts in a temperature range of 4.2-300 K are reported. The analysis of the temperature dependences of the g-factors points to significant differences between Jahn-Teller Cu(H2O)62+ complexes in the ammonium and potassium compounds. In the ammonium salts the energy difference 12, between the ground and excited configurations, is found to be temperature dependent. This is explained by the lattice contribution to the adiabatic potential. Various mechanisms of such an influence are proposed. For the discussed case it is suggested that thermal librations of the ammonium groups will change the strength of the hydrogen bonds between the sulphate groups and water octahedra and in this way influence the Jahn-Teller complex.

An unsteady flow around a transversal circular cylinder has been analyzed on the basis of solution of Navier-Stokes and Reynolds equations, closed, in the latter case, using one-and two-parameter differential models of turbulence, by the implicit factorized method with the use of different-density structured and nonstructured grids. Solvers of specialized multiblock and universal packages have been tested.Introduction. Modern computational technologies for solving various thermophysical and aerohydrodynamical problems are characterized by the following factors: a) packages are used at the industrial stage of numerical simulation, b) calculations are paralleled with the use of multiprocessors, which is considered as the most economical way of increasing the computational efficiency, and c) different-scale problems are represented on multiblock grids, which is considered as the most rational method of solving such problems [1]. In the present numerical investigation, we considered the genesis of multiblock computational technologies [2] based on solution of Navier-Stokes and Reynolds equations by the factorized implicit method on a set of intersecting different-scale grids, including sliding ones, used for solving the classical problems on unsteady laminar and turbulent flows around a circular cylinder. Prominence was given to the comparative analysis of the specialized package VP2/3, developed on the basis of multiblock computational technologies, with the known universal package FLUENT [3]. Estimation of the acceptability of two semiempirical models of turbulence -the one parameter Spalart-Allmaras model of eddy viscosity (SA) [4] and the two-parameter Menter zonal model of shear-stress transfer (MSST) [5] -has also been the subject of the present investigation.As is known, the progress made in computational hydrodynamics in the last few decades is comparable to the progress made in the classical sciences over several centuries. These advances resulted from the rapid development of computational engineering; mathematical models of turbulence, combustion, radiative heat exchange, and others; and efficient numerical methods. Comparatively recently (in the lifetime of one generation -in the late 1960s-early 1970s), application programs written in one of the algorithmic programming languages (ALGOL or FORTRAN most often) served as the information basis of calculations. These programs were activated in large (BESM6 or CDC7600) computers in centers of collective use, and the results obtained were processed practically by hand.Today, at the industrial stage of development of computational hydrodynamics [6], application programs comprise universal and specialized packages representing complex multicomponent intelligence systems written, as a rule, in object-oriented programming languages and having a "triad" structure: grid generator-solver-graphic data interpreter. A package involves catalogs of mathematical models and data of controlling physical processes, from elements of which a desired problem is formed. Packages a...

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The effect of temperature and hydrostatic pressure on the spin-Hamiltonian parameter for in elpasolite is studied up to a pressure of 700 MPa over the temperature range 180 - 360 K. It is found that 56% of the temperature change in is caused by the spin - phonon interaction, and the remaining 44% is related to the thermal expansion of the crystal. The temperature at which the phase transition from the cubic to the tetragonal phase occurs is a linear function of pressure, with the pressure coefficient . The dependence of on the lattice constant and hydrostatic pressure is interpreted within the rigid-sphere model. No precursive behaviour above is observed.

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