Astron. Astrophys. 358, 45-56 (2000)

SPH simulations of gas flow in barred galaxies. Effect of hydrodynamical and numerical parameters

P.A. Patsis ^1,2 and E. Athanassoula <sup>3

1</sup> Research Center for Astronomy, Academy of Athens, 14 Anagnostopoulou St., 10673 Athens, Greece
² Astronomisches Rechen-Institut Heidelberg, Mönchhofstrasse 13, 69120 Heidelberg, Germany
³ Observatoire de Marseille, 2 Place Le Verrier, 13248 Marseille cedex 4, France

Received 12 August 1999 / Accepted 25 February 2000

Abstract

We use SPH to calculate the gas response in a potential representing a strongly barred galaxy. We examine the dependence of the morphology and of the inflow rate of this response on hydrodynamical and numerical parameters used in the simulations. In particular we study the effects of the sound speed, the rate of growth of the bar and the number of particles used in our models. We also investigate the appropriate value of the artificial viscosity to be used in the models, delimiting a region of values within which the flow is correctly described. We conclude that models with number of particles have similar overall morphology, although their inflow rates may differ. The existence of straight-line "dust-lane" shocks is not affected by any of the above mentioned parameters. They do, however, influence the location, the strength, the width and the longevity of these shocks. At sound speed =20 km s^-1 we find the longer lasting (for about 10 rotational periods of the bar) sharply described shocks. The "x₂" region morphology changes slightly during the evolution of the models. The sound speed influences both this rate of change and the inflow rate of he gas. Finally introducing the bar abruptly from the beginning gives a response morphology which is different from what is obtained if the bar is introduced slowly over two pattern rotations; this also influences the inflow rate.

Key words: ISM: kinematics and dynamics galaxies: kinematics and dynamics galaxies: spiral galaxies: structure

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Contents

• 1. Introduction
• 2. Models and computing miscelanea
  • 2.1. The potential
  • 2.2. SPH characteristics
  • 2.3. The set-up of the models
  • 2.4. Simulations
• 3. Results
  • 3.1. The effect of sound speed
    • 3.1.1. The "dust-lanes" shocks
    • 3.1.2. The "x₂" area
  • 3.2. The growth rate of the bar
  • 3.3. The effect of number of particles
  • 3.4. The artificial viscosity
• 4. Conclusions
• Acknowledgements
• References

© European Southern Observatory (ESO) 2000

Online publication: June 26, 2000
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