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Because of their low gravitational energy, low-mass galaxies are seriously affected by energetical processes in their interstellar medium, such as supernova explosions, or by gravitational perturbations, e.g., by neighbouring galaxies. This can reasonably explain their variety of morphological types. If the evolutionary timescales of galaxies are predominantly determined by internal processes, the multi-phase character as well as star-gas interactions and phase transitions have to be taken into account. For this purpose we have developed a numerical treatment of the dynamical behaviour of gas and stars, which also accounts for the metal dependence of some processes and which can trace the chemical evolution for different elements. This so-called chemodynamical treatment is described in detail in Theis et al. (1992) and Samland et al. (1997). It considers three stellar components and devides the gas into clouds (CM, with a mass spectrum) and a hot intercloud medium (ICM). Since the element enhancement of the interstellar medium is produced by different processes with different lifetimes of their progenitors, O, Fe, and N are used as tracer elements to represent supernovae type II (SNell), type la (SNela), and planetary nebulae (PNe) contributions. While supernovae form the ICM, PNe only attribute to the CM so that only mixing effects of both gas phases can alter abundance ratios.
Due to limited computer capacities the first chemodynamical simulations of dwarf galaxies could be performed only one-dimensionally so far (see e.g., Hensler et al. 1993, 1998). The recently developed two-dimensional chemodynamical code CoDEx (Samland 1994) was first applied to massive disk galaxies and produced models of which a particular one could represent various chemical and structural observations of the Milky Way with striking agreement (Samland et al. 1997).
