[1] It has been suggested that drift loss to the magnetopause can be one of the major loss mechanisms contributing to relativistic electron flux dropouts. In this study, we examine details of relativistic electrons' drift physics to determine the extent to which the drift loss through the magnetopause is important to the total loss of the outer radiation belt. We have numerically computed drift paths of relativistic electrons' guiding center for various pitch angles, various measurement positions, and different solar wind conditions using the Tsyganenko T02 model. We specifically demonstrate how the drift loss effect depends on these various parameters. Most importantly, we present various estimates of relative changes of the omnidirectional flux of 1 MeV electrons between two different solar wind conditions based on a simple form of the directional flux function. For a change of the dynamic pressure from 4 nPa to 10 nPa with a fixed IMF B Z = 0 nT, our estimate indicates that after this increase in pressure, the equatorial omnidirectional flux at midnight near geosynchronous altitude decreases by $56 to $97%, depending on the specific pitch angle dependence of the directional flux. The effect rapidly decreases at regions earthward of geosynchronous orbit and shows a general trend of decrease away from midnight. For a change of the IMF B Z from 0 nT to À15 nT with a fixed dynamic pressure of 4 nPa, the relative decrease of the omnidirectional flux at geosynchronous altitude on the nightside is much smaller than that for the pressure increase, but its effect becomes substantial only beyond geosynchronous orbit. Possibilities exist that our results may change to some extent for a different magnetospheric model than the one used here.

[1] Close to the dayside magnetopause, there is a region of space where each field line has two magnetic field minima, one near each cusp. That region is located around local noon, and extends about 1-2 R e from the magnetopause. Particles that enter this region with equatorial pitch angles sufficiently close to 90°will cross the dayside not along an equatorial path, but along one of the two branches on either side of the equatorial plane. The two branches are joined again past local noon. This process of drift-shell bifurcation (DSB) is nonadiabatic even under static conditions. Two physical mechanisms can cause this nonadiabaticity: one that is operative for nearly all magnetospheric magnetic field configurations and another that depends on a particular combination of north-south and east-west asymmetry in the magnetic field. This paper deals only with the first mechanism. For configurations with north-south and east-west symmetry, DSB changes the second invariant I of the motion by a small amount that is of the order of the gyroradius (the first invariant is intact). For near-equatorial particles (I % 0) the change can be significantly larger. Assuming north-south and dawn-dusk symmetry, we present general theoretical expressions for the second-invariant jump DI, which can be applied to a variety of magnetic field models. The results show that DI is sensitively dependent on the bounce phase of the particle at the bifurcation line. The RMS value of DI over a bounce-phase ensemble increases with decreasing mirror field and with increasing kinetic energy. We verify these results with test-particle simulations using model magnetic fields.

[1] We study trapped energetic particles in the terrestrial magnetosphere undergoing drift shell bifurcation in the magnetic field lacking north-south and east-west symmetry. Drift shell bifurcation occurs near the dayside magnetopause, where, due to the solar wind compression, the field strength has a local maximum near the equatorial plane. As a result, a charged particle may become temporarily trapped in one of the hemispheres while traversing the region. Although this phenomenon has been known for a long time, only recently were the associated second invariant changes quantified for the magnetic field with north-south and east-west symmetry. Here we show that if the magnetic field lacks such symmetry, the effect is more significant. We calculate changes to the second invariant of keV to MeV electrons in Tsyganenko magnetic fields with nonzero interplanetary magnetic field (IMF) B Y component. The changes are on the order of the invariant itself, and thus, this effect is much larger than for the case of symmetric magnetic field (when the particle gyroradius is much less than the magnetospheric scale length). We also quantify the effect for different values of the solar wind dynamic pressure, IMF B Z component, and the Dst index with the Tsyganenko magnetic field T02. We find that Dst has no noticeable role, while larger solar wind ram pressure increases the second invariant changes. We verify our calculations by numerical integration of the guiding center drift equations and discuss properties of different versions of these equations.Citation: Wan, Y., S. Sazykin, R. A. Wolf, and M. K. Öztürk (2010), Drift shell bifurcation near the dayside magnetopause in realistic magnetospheric magnetic fields,

Turbulent blood flow in medical devices contributes to blood trauma, yet the exact mechanism(s) have not been fully elucidated. Local turbulent stresses, viscous stresses, and the rate of dissipation of the turbulent kinetic energy have been proffered as hypotheses to describe and predict blood damage. In this work, simulations of experiments in a Couette flow viscometer and a capillary tube were used to examine extensive properties of the turbulent flow field and to investigate contributing factors for red blood cell hemoglobin release in turbulence by eddy analysis. It was found that hemolysis occurred when dissipative eddies were comparable in size to the red blood cells. The Kolmogorov length scale was used to quantify the size of smaller turbulent eddies, indicating correspondence of hemolysis with number and surface area of eddies smaller than about 10 μm when a k-ε turbulence model is adopted.