Труды сотрудников ИВМ СО РАН

/ N.V. Erkaev, V.S. Semenov, H.K. Biernat // Phys. Plasmas. - 2012. - Vol. 19, Is. 6. - Ст. 62905, DOI 10.1063/1.4725506. - Cited References: 22. - This work is supported by RFBR Grants Nos. 12-05-00152-a and 12-05-00918-a, and also by St. Petersburg University grant. V. S. S. and H. K. B. are supported from the FP7 Programme under Grant No. 269198-Geoplasmas (Marie Curie Exchange Scheme). Additional support is due to the Austrian "Fonds zur Forderung der wissenschaftlichen Forschung" under Project I 193-N16 and the "Verwaltungsstelle fur Auslandsbeziehungen" of the Austrian Academy of Sciences. . - ISSN 1070-664XРУБ Physics, Fluids & Plasmas

Аннотация: Magnetic filament approach is applied for modeling of nonlinear "kink"-like flapping oscillations of thin magnetic flux tubes in the Earth's magnetotail current sheet. A discrete approximation for the magnetic flux tube was derived on a basis of the Hamiltonian formulation of the problem. The obtained system of ordinary differential equations was integrated by method of Rosenbrock, which is suitable for stiff equations. The two-dimensional exact Kan's solution of the Vlasov equations was used to set the background equilibrium conditions for magnetic field and plasma. Boundary conditions for the magnetic filament were found to be dependent on the ratio of the ionospheric conductivity and the Alfven conductivity of the magnetic tube. It was shown that an enhancement of this ratio leads to the corresponding increase of the frequency of the flapping oscillations. For some special case of boundary conditions, when the magnetic perturbations vanish at the boundaries, the calculated frequency of the "kink"-like flapping oscillations is rather close to that predicted by the "double gradient" analytical model. For others cases, the obtained frequency of the flapping oscillations is somewhat larger than that from the "double gradient" theory. The frequency of the nonlinear flapping oscillations was found to be a decreasing function of the amplitude. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4725506]


Доп.точки доступа:
Erkaev, N.V.; Еркаев, Николай Васильевич; Semenov, V.S.; Biernat, H.K.

[Text] / O.V. Sadovskaya, V.M. Sadovskii // Acoust. Phys. - 2010. - Vol. 56, Is. 6. - P942-950, DOI 10.1134/S1063771010060199. - Cited References: 19. - This study was supported by the Russian Foundation for Basic Research (project no. 08-01-00148), Complex Fundamental Research Program no. 2 of the Presidium of the Russian Academy of Sciences, and Siberian Division of the Russian Academy of Sciences (Interdisciplinary Integration Project no. 40). . - 9. - ISSN 1063-7710РУБ Acoustics

Аннотация: Oscillatory processes in media with microstructure under the action of concentrated impulse and time-periodic perturbations are analyzed within the Cosserat elasticity theory. According to the results of computations, such media are characterized by a resonance frequency equal to the frequency of natural oscillations of particle rotational motion. This frequency is a phenomenological parameter of a material. It was established that the oscillatory rotation of particles changes for monotone rotational motion with increasing intensity of shear strains.


Доп.точки доступа:
Sadovskaya, O.V.; Садовская, Оксана Викторовна; Sadovskii, V.M.; Садовский, Владимир Михайлович

[Text] / N. V. Erkaev, V. S. Semenov, H. K. Biernat // Geophys. Res. Lett. - 2008. - Vol. 35, Is. 2. - Ст. L02111, DOI 10.1029/2007GL032277. - Cited References: 13 . - ISSN 0094-8276РУБ Geosciences, Multidisciplinary

Аннотация: A new kind of magnetohydrodynamic waves are analyzed for a current sheet in a presence of a small normal magnetic field component varying along the sheet. As a background, two simplified models of a current sheet are considered with a uniform and nonuniform current distributions in the current sheet. On a basis of these two models, the flapping-type waves are obtained which are related to a coexistence of two gradients of the tangential and normal magnetic field components along the normal and tangential directions with respect to the current sheet. A stable situation for the current sheet is associated with a positive result of the multiplication of the two magnetic gradients, and unstable ( wave growth) condition corresponds to a negative result of the product. In the stable region, the "kink''-like wave mode is interpreted as so called flapping waves observed in the Earth's magnetotail current sheet.


Доп.точки доступа:
Erkaev, N.V.; Еркаев, Николай Васильевич; Semenov, V.S.; Biernat, H.K.

[Text] / D. F. Vogl [et al.] // Planet Space Sci. - 2003. - Vol. 51, Is. 12. - P715-722, DOI 10.1016/S0032-0633(03)00108-9. - Cited References: 28 . - ISSN 0032-0633РУБ Astronomy & Astrophysics

Аннотация: In this paper, we concentrate on the analysis of the anisotropic Rankine-Hugoniot equations for perpendicular and oblique fast shocks. In particular, as additional information to the anisotropic set of equations, the threshold conditions of the fire-hose and mirror instability are used to bound the range of the pressure anisotropy downstream of the discontinuity. These anisotropic threshold conditions of the plasma instabilities are obtained via a kinetic approach using a generalized Lorentzian distribution function, the so-called kappa distribution function. Depending on up-stream conditions, these instabilities further define stable and unstable regions with regard to the pressure anisotropy downstream of the shock. The calculations are done for different upstream Alfven Mach numbers. We found that low values of the parameter kappa reduce the pressure anisotropy downstream of the shock. (C) 2003 Elsevier Ltd. All rights reserved.


Доп.точки доступа:
Vogl, D.F.; Langmayr, D.; Erkaev, N.V.; Еркаев, Николай Васильевич; Biernat, H.K.; Farrugia, C.J.; Muhlbachler, S.

[Text] / D. F. Vogl [et al.] // HELIOSPHERE AT SOLAR MAXIMUM. Ser. ADVANCES IN SPACE RESEARCH : PERGAMON-ELSEVIER SCIENCE LTD, 2003. - Vol. 32: D1 1/D2 1/E3 1 Symposium of COSPAR Scientific Commission D held at the 34th COSPAR Scientific Assembly/2nd Space Congress (OCT 10-19, 2002, HOUSTON, TEXAS), Is. 4. - P519-523, DOI 10.1016/S0273-1177(03)00336-3. - Cited References: 18 . - ISBN 0273-1177РУБ Engineering, Aerospace + Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: In this paper, we concentrate on the solution of the anisotropic Rankine-Hugoniot equations for inclined fast shocks taking into account a new approach in closing the set of equations. In particular, the threshold conditions of the fire-hose and that of the mirror instability, obtained in a kinetic approach using the so-called kappa distribution function, are used to bound the range of the pressure anisotropy downstream of the discontinuity. We study the variation of the density across the shock for a given Alfven Mach number and upstream pressure anisotropy and find that the parameter kappa is most sensitive to stable plasma conditions, i.e. low values of kappa reduce the pressure anisotropy downstream of the discontinuity. (C) 2003 COSPAR. Published by Elsevier Ltd. All rights reserved.


Доп.точки доступа:
Vogl, D.F.; Langmayr, D.; Erkaev, N.V.; Еркаев, Николай Васильевич; Biernat, H.K.; Farrugia, C.J.; Muhlbachler, S.

[Text] / C. J. Farrugia [et al.] // SPACE WEATHER 2000. Ser. ADVANCES IN SPACE RESEARCH-SERIES : PERGAMON-ELSEVIER SCIENCE LTD, 2003. - Vol. 31: PSW1/C0 1/D0 5/E2 5/F2 0 Symposium of the COSPAR Scientific Panel on Space Weather held at the 33rd COSPAR Scientific Assembly (JUL, 2000, WARSAW, POLAND), Is. 4. - P1105-1110, DOI 10.1016/S0273-1177(02)00889-X. - Cited References: 16 . - ISBN 0273-1177РУБ Engineering, Aerospace + Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: With its similar to12 h-long period of strongly northward magnetic field, the coronal mass ejection which passed Earth on April 11, 1997 affords an excellent opportunity of studying Kelvin-Helmholtz (KH) activity at the dayside magnetopause as a function of the clock angle, theta, of the interplanetary field (IMF). A correlation between the wavelength of the KH waves and theta may be expected on the basis of our recent model, where activity is generated in strips which broaden as theta decreases. We identify two 2-hour long intervals of small, but different, clock angles, and make a preliminary test of model predictions, using records from two ground magnetometer chains, both on the dayside. Taking into account the local time of the magnetometer arrays and the geometry of the KH-active strips, we show that the resonant stations measured considerably more spectral power density in the 3-4 mHz range during the phase with smaller theta. Moreover, as theta increases, the spectral power spectrum shifted to higher frequencies that were almost absent for smaller theta. (C) 2003 COSPAR. Published by Elsevier Science Ltd. All rights reserved.


Доп.точки доступа:
Farrugia, C.J.; Gratton, F.T.; Torbert, R.B.; Bender, L.; Gnavi, G.; Ogilvie, K.W.; Erkaev, N.V.; Еркаев, Николай Васильевич; Lepping, R.P.; Stauning, P.

[Text] / C. J. Farrugia [et al.] // J. Geophys. Res-Space Phys. - 2001. - Vol. 106, Is. A12. - P29373-29385, DOI 10.1029/2001JA000034. - Cited References: 42 . - ISSN 0148-0227РУБ Astronomy & Astrophysics

Аннотация: We carry out a first comparison with spacecraft measurements of our recent three-dimensional, one-fluid magnetohydrodynamic (MHD) model for the anisotropic magnetosheath [Erkaev et al., 1999], using data acquired by the Wind spacecraft on an inbound magnetosheath pass on December 24, 1994. The spacecraft trajectory was very close to the stagnation streamline, being displaced by less than 1/2 hour from noon and passing at low southern magnetic latitudes (similar to4.5degrees). All quantities downstream of the bow shock are obtained by solving the Rankine-Hugoniot equations taking the pressure anisotropy into account. In this application of our model we close the MHD equations by a "bounded anisotropy" ansatz using for this purpose the inverse correlation between the proton temperature anisotropy, A(p) (equivalent to T-pperpendicular to/T-pparallel to - 1) and the proton plasma beta parallel to the magnetic field beta(pparallel to) observed on this pass when conditions are steady. In the model the total perpendicular pressure is prescribed and not obtained self-consistently. For all quantities studied we find very good agreement between the predicted and the observed profiles, indicating that the bounded anisotropy method of closing the magnetosheath equations, first suggested by Denton et al. [1994], is valid and reflects the physics of the magnetosheath well. We assess how sensitive our model results are to different parameters in the A(p) = alpha(0)beta(pparallel to)(-alpha1) (alpha(1) 0) relation, taking for al the two limiting values (0.4, 0.5) resulting from the two-dimensional hybrid simulations of Gary et al. [1997], and varying alpha(0) in the range 0.6 - 0.8. Input solar wind conditions are as measured on this pass. In general, the model profiles depend more strongly on alpha(0) than on al. In particular, decreasing alpha(0) narrows the width of the plasma depletion layer (PDL) and widens the mirror stable region. For the lowest value of alpha(0) the mirror stable region extends sunward of the outer edge of the PDL. For the other two values of alpha(0) and regardless of the value of al, it is contained within the PDL. Finally, we also study phenomenological double-polytropic laws and find polytropic indices gamma(perpendicular to) approximate to 1 and gamma(parallel to) approximate to 1.5. These results agree well with those of Hau et al. [1993] inferred from Active Magnetospheric Particle Tracer Explorers/ Ion Release Module data on a crossing of the near-subsolar magnetosheath.


Доп.точки доступа:
Farrugia, C.J.; Erkaev, N.V.; Еркаев, Николай Васильевич; Vogl, D.F.; Biernat, H.K.; Oieroset, M.; Lin, R.P.; Lepping, R.P.

[Text] / C. J. Farrugia [et al.] // J. Geophys. Res-Space Phys. - 1998. - Vol. 103, Is. A4. - P6703-6727DOI 10.1029/97JA03248. - Cited References: 39 . - РУБ Astronomy & Astrophysics

Аннотация: We present maximum growth rate charts of the Kelvin-Helmholtz (KH) and Rayleigh-Taylor (RT) instabilities at the dayside magnetopause (MP), considering two orientations of the interplanetary magnetic field (IMF) (due north and 30 degrees west of north). We input parameters in the plasma depletion layer calculated from an MHD code. We study both a sharp MP transition and an MP with an attached boundary layer ("thin" and "thick" approximations, respectively). Our analysis applies to wavelengths (lambda) from similar to 2 x 10(3) km to less than or equal to 9 R-E. Thin model results are as follows: For a stationary MP and due north IMF, the off-noon, low-latitude MP is very low shear (less than or equal to 10 degrees) and is substantially KH active. With an IMF inclined to north, extremely low shear, KH-active regions are confined to two strips, one in each hemisphere, where short lambda perturbations are generated, which propagate as surface ripples on the high-latitude, duskside MP. For a sunward accelerating magnetopause and IMF north, a large part of the MP is unstable. With an inclined IMF, the KH+RT unstable strips are broader and growth rates are higher. Thick model results are as follows: For IMF due north and a stationary MP, the middle-to high-latitude MP is stable. At middle to low latitudes, the inner edge of the boundary layer (IEBL) is active, except fora 2-hour local time band on either side of noon. For the inclined IMF, the MP is stable for long lambda, with activity for short lambda confined to two strips, as before, with slightly reduced growth rates. For the IEBL, a clear dawn-dusk asymmetry in KH activity is evident. When the MP accelerates sunward and the IMF points north, we have to consider also the lambda of the perturbation. For short lambda, growth rates are enhanced with respect to stationarity at both the NIP and the IEBL. While there are extensive regions of negligible growth at the MP, the entire IEBL is RT + KH unstable. We give an example of a long lambda perturbation where both interfaces are coupled and oscillate together. Finally, for an inclined IMF, we have at the MP unstable strips which are wider and have higher growth rates. The IEBL, by contrast, is completely destabilized, with larger growth rates than under stationary conditions.

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Доп.точки доступа:
Farrugia, C.J.; Gratton, F.T.; Bender, L.; Biernat, H.K.; Erkaev, N.V.; Еркаев, Николай Васильевич; Quinn, J.M.; Torbert, R.B.; Denisenko, V.V.; Денисенко, Валерий Васильевич

/ L. A. Kompaniets // Russ. J. Numer. Anal. Math. Model. - 1996. - Vol. 11, Is. 3. - P205-221, DOI 10.1515/rnam.1996.11.3.205. - Cited References: 20 . - ISSN 0927-6467РУБ Engineering, Multidisciplinary + Mathematics, Applied

Аннотация: We consider the difference schemes for the one-dimensional versions of nonlinear dispersive shallow water models. We analyse the dissipative and dispersive properties and give the results of numerical calculations.

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Держатели документа:
Computer Center, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk 660036, Russian Federation
ИВМ СО РАН

Доп.точки доступа:
Kompaniets, L.A.; Компаниец, Лидия Алексеевна