OVERVIEW

One–dimensional numerical simulations of a large–scale flow of interstellar gas in galactic spiral density waves were produced using the approach described by Roberts (1969), Shu et al. (1972, 1973), Woodward (1975), Marochnik et al. (1983), Lubow et al. (1986), and Berman et al. (1990).

We have employed a two–phase model for the initial state of the interstellar medium (ISM). Thermal processes and self–gravitation of the gas were taken into account. Magnetic fields were not included in this version of the mathematical model. A discussion on the role of the magnetic field and status of the two–phase model of ISM versus Supernova–dominated model can be found in Marochnik and Suchkov (1991).

We have used the Schmidt model of the galaxy and the following parameters of its spiral structure: Ωp = 23, 24, and 13.5 km s-1 kpc-1 (the angular velocity of the spiral pattern), F = 10% (the gravitational field of a spiral arm). The right-hand side of the energy equation is L = n(nΛ – Γ), where nΛ(T) and Γ are the standard cooling and heating functions, respectively (Penston 1970).

Numerical simulations of the interstellar gas flow have been produced for a number of galactocentric distances, R = 4, 5, 6, 8, 10 kpc and two different values of the initial density of the interstellar gas, n0 = 0.05 and 0.5 cm-3. Figure 1 demonstrates one of the examples simulated.