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Title: SIMULATIONS OF THE BOUNDARY LAYER BETWEEN A WHITE DWARF AND ITS ACCRETION DISK

Abstract

Using a 2.5D time-dependent numerical code we recently developed, we solve the full compressible Navier-Stokes equations to determine the structure of the boundary layer (BL) between the white dwarf (WD) and the accretion disk in nonmagnetic cataclysmic variable systems. In this preliminary work, our numerical approach does not include radiation. In the energy equation, we either take the dissipation function ({phi}) into account or we assume that the energy dissipated by viscous processes is instantly radiated away ({phi} = 0). For a slowly rotating nonmagnetized accreting WD, the accretion disk extends all the way to the stellar surface. There, the matter impacts and spreads toward the poles as new matter continuously piles up behind it. We carry out numerical simulations for different values of the alpha-viscosity parameter ({alpha}), corresponding to different mass accretion rates. In the high viscosity cases ({alpha} = 0.1), the spreading BL sets off a gravity wave in the surface matter. The accretion flow moves supersonically over the cusp making it susceptible to the rapid development of gravity wave and/or Kelvin-Helmholtz shearing instabilities. This BL is optically thick and extends more than 30 deg. to either side of the disk plane after only 3/4 of a Keplerianmore » rotation period (t{sub K} = 19 s). In the low viscosity cases ({alpha} = 0.001), the spreading BL does not set off gravity waves and it is optically thin.« less

Authors:
;  [1];
  1. Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States)
Publication Date:
OSTI Identifier:
21336009
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 702; Journal Issue: 2; Other Information: DOI: 10.1088/0004-637X/702/2/1536; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; BOUNDARY LAYERS; COMPUTERIZED SIMULATION; GRAVITY WAVES; MATTER; NAVIER-STOKES EQUATIONS; NOVAE; TIME DEPENDENCE; WHITE DWARF STARS

Citation Formats

Balsara, Dinshaw S, Fisker, Jacob Lund, Godon, Patrick, and Sion, Edward M. SIMULATIONS OF THE BOUNDARY LAYER BETWEEN A WHITE DWARF AND ITS ACCRETION DISK. United States: N. p., 2009. Web. doi:10.1088/0004-637X/702/2/1536; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
Balsara, Dinshaw S, Fisker, Jacob Lund, Godon, Patrick, & Sion, Edward M. SIMULATIONS OF THE BOUNDARY LAYER BETWEEN A WHITE DWARF AND ITS ACCRETION DISK. United States. doi:10.1088/0004-637X/702/2/1536; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
Balsara, Dinshaw S, Fisker, Jacob Lund, Godon, Patrick, and Sion, Edward M. Thu . "SIMULATIONS OF THE BOUNDARY LAYER BETWEEN A WHITE DWARF AND ITS ACCRETION DISK". United States. doi:10.1088/0004-637X/702/2/1536; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
@article{osti_21336009,
title = {SIMULATIONS OF THE BOUNDARY LAYER BETWEEN A WHITE DWARF AND ITS ACCRETION DISK},
author = {Balsara, Dinshaw S and Fisker, Jacob Lund and Godon, Patrick and Sion, Edward M.},
abstractNote = {Using a 2.5D time-dependent numerical code we recently developed, we solve the full compressible Navier-Stokes equations to determine the structure of the boundary layer (BL) between the white dwarf (WD) and the accretion disk in nonmagnetic cataclysmic variable systems. In this preliminary work, our numerical approach does not include radiation. In the energy equation, we either take the dissipation function ({phi}) into account or we assume that the energy dissipated by viscous processes is instantly radiated away ({phi} = 0). For a slowly rotating nonmagnetized accreting WD, the accretion disk extends all the way to the stellar surface. There, the matter impacts and spreads toward the poles as new matter continuously piles up behind it. We carry out numerical simulations for different values of the alpha-viscosity parameter ({alpha}), corresponding to different mass accretion rates. In the high viscosity cases ({alpha} = 0.1), the spreading BL sets off a gravity wave in the surface matter. The accretion flow moves supersonically over the cusp making it susceptible to the rapid development of gravity wave and/or Kelvin-Helmholtz shearing instabilities. This BL is optically thick and extends more than 30 deg. to either side of the disk plane after only 3/4 of a Keplerian rotation period (t{sub K} = 19 s). In the low viscosity cases ({alpha} = 0.001), the spreading BL does not set off gravity waves and it is optically thin.},
doi = {10.1088/0004-637X/702/2/1536; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 702,
place = {United States},
year = {2009},
month = {9}
}