V. B. Kharchenko

Charge-transfer induced EUV and soft X-ray emissions in the heliosphere

We study the EUV/soft X-ray emission generated by charge transfer between solar wind heavy ions and interstellar H and He neutral atoms in the inner Heliosphere. We present heliospheric maps and spectra for stationary solar wind, depending on solar cycle phase, solar wind anisotropies and composition, line of sight direction and observer position. A time-dependant simulation of the X-ray intensity variations due to temporary solar wind enhancement is compared to XMM Newton recorded data of the Hubble Deep Field North observation (Snowden et al. 2004). Results show that the heliospheric component can explain a large fraction of the line intensity below 1.3 keV, strongly attenuating the need for soft X-ray emission from the Local Interstellar Bubble.We study the EUV/soft X-ray emission generated by charge transfer between solar wind heavy ions and interstellar neutral atoms and variations of the X-ray intensities and spectra with the line of sight direction, the observer location, the solar cycle phase and the solar wind anisotropies, and a temporary enhancement of the solar wind similar to the event observed by Snowden et al. (2004) during the XMM-Hubble Deep Field North exposure. Methods.Using recent observations of the neutral atoms combined with updated cross-sections and cascading photon spectra we have computed self-consistent distributions of interstellar hydrogen, helium and highly charged solar wind ions for a stationary solar wind and we have constructed monochromatic emission maps and spectra. We have evaluated separately the contribution of the heliosheath and heliotail, and included X-ray emission of the excited solar wind ions produced in sequential collisions to the signal. Results.In most practicable observations, the low and medium latitude X-ray emission is significantly higher at minimum activity than at maximum, especially around December. This occurs due to a strong depletion of neutrals during the high activity phase, which is not compensated by an increase of the solar wind flux. For high latitudes the emission depends on the ion species in a complex way. Intensity maps are in general significantly different for observations separated by six-month intervals. Secondary ions are found to make a negligible contribution to the X-ray line of sight intensities, because their density becomes significant only at large distances. The contribution of the heliosheath-heliotail is always smaller than 5%. We can reproduce both the intensity range and the temporal variation of the XMM-HDFN emission lines in the 0.52-0.75 keV interval, using a simple enhanced solar wind spiral stream. This suggests a dominant heliospheric origin for these lines, before, during and also after the event.

Verification of the multiblock computational technology in calculating laminar and turbulent flow around a spherical hole on a channel wall

A methodological numerical investigation of the three-dimensional flow of an incompressible viscous fluid around a deep spherical hole on a channel wall has been carried out within the framework of the multiblock approach on the set of intersecting rectangular and cylindrical grids.

Modeling of the influence of viscosity on the tornado heat exchange in turbulent flow around a small hole on the plane

The influence of viscosity on turbulent flow around a small spherical hole on the plane and on vortex heat exchange is analyzed numerically.

Numerical analysis of the influence of angle of attack on turbulent flow around a thick goettingen airfoil with vortex cells

On the basis of the solution by multi-block computational technologies of Reynolds equations closed with the aid of the equations of the model of Menter’s shear stresses transfer, an analysis of the flow around a thick airfoil of classical geometry with vortex cells is given at an arrangement of suction from the surface of central bodies placed inside them. The suction velocities, angles of attack, and location of vortex cells on the contour are determined, under which the flow around an airfoil of 35,2% thickness is ensured close to a separation-free flow, for high Reynolds numbers (Re = 105). The integral force characteristics of the Goettingen and EKIP profiles are compared for the distributed and concentrated suction in vortex cells.

Calculation of Nonstationary Flow Around a Circular Cylinder within the Framework of Multiblock Computational Technologies

A methodological numerical investigation of nonstationary flow of an incompressible viscous fluid around a circular cylinder has been carried out within the framework of the multiblock approach on a set of intersecting rectangular and cylindrical grids.

Calculation of a three-dimensional flow of a viscous incompressible liquid in the neighborhood of a shallow well on a flat surface

A three-dimensional flow in the neighborhood of a shallow well on a plane was simulated numerically on the basis of a solution of the Reynolds equations written in curvilinear nonorthogonal coordinates and closed by a two-parametric dissipative model of turbulence.

Numerical Simulation of the Unsteady Laminar Flow Past a Circular Cylinder with a Perforated Sheath

The unsteady two-dimensional laminar flow past a circular cylinder encased in a perforated sheath is numerically simulated. On the basis of the calculated results a technique for controlling the wake flow by diverting a portion of the flow from the forward stagnation point through internal ducts to orifices in the sheath located in the separation zone, is analyzed.

Numerical Simulation of Nonstationary Turbulent Flow around an Automobile Profile Near a Mobile Screen

A numerical investigation of nonstationary turbulent flow of an incompressible viscous fluid around the profile of a Volkswagen automobile near a mobile screen has been carried out on the basis of solution of the Reynolds equations closed using a two-parameter dissipation model of turbulence by the finite-volume method.

NUMERICAL MODELING OF LAMINAR CIRCULATION FLOW IN A CUBIC CAVITY WITH A MOVING FACE

Laminar circulation flow in a cubic cavity with a moving face is numerically analyzed. The jet‐vortex elements of the flow which develop in the cavity are identified.