The evolution of cold dark matter (CDM) models containing both baryonic matter and dark matter has been computed for a postrecombination Friedmann-Robertson-Walker universe utilizing a locally valid Newtonian approximation to model a representative piece of the universe whose size is much less than the horizon. Hydrodynamics is treated with a higly developed Eulerian hydrodynamic code. A standard Particle-Mesh (PM) code to calculate the motion of collisionless particles is coupled with this hydrodynamic code. We model the standard CDM scenario, adopting the parameters h = H0/100 km s-1 Mpc-1 = 0.5, OMEGA = 1.0, OMEGA(b) = 0.06 with amplitude of the perturbation spectrum fixed by the requirement that (delta-M/M)rms = 1/b = 1/1.5 in a 8h-1 Mpc top hat sphere at z = 0. Four different boxes are simulated with box sizes of L = (64, 16, 4, 1)h-1 Mpc, respectively, the smaller boxes providing good resolution but little valid information due to the absence of large scale power. We use 128(3) approximately 10(6.3) baryonic cells and an equal number dark matter particles. In addition to the dark matter we follow separately six baryonic species (H, H+, He, He+, He++, e-) with allowance for both (nonequilibrium) collisional and radiative ionization in every cell. The background radiation field is also followed in detail with allowance made for bremsstrahlung and free-bound emission as well as ionization losses. However, in computing the thermal changes of the gas, we allow for both line and continuum processes as well as Compton interactions with the cosmic background radiation (CBR) and X-ray background radiation (XBR) fields. The mean final Zel'dovich-Sunyaev y parameter is estimated to be <y> = (1.3 +/- 0.6) x 10(-6), below currently attainable observations, with a rms fluctuation of approximately <delta-y> = (1.4 +/- 0.7) x 10(-6) on arcminute scales. Of greater interest, this model can make a nontrivial fraction of the soft X-ray background in the 0.1-1.0 KeV range. Comparing computations to observation we can set a limit for OMEGA(b) of less-than-or-equal-to 0.037b2.2, which is consistent with the latest cosmic nucleosynthetic values. The model fails by a large factor to produce enough ionization either by shocks or radiation to satisfy the high-redshift Gunn-Peterson test. Addition of UV radiation from stars in forming galaxies may remedy this problem. We also examine the properties of X-ray emitting regions and the two-point correlation functions of the "galaxies"-the cooled, bound regions. The rate of galaxy formation peaks at a relatively late epoch (z < 1). With regard to mass function, the smallest objects are stabilized against collapse by thermal energy: the mass-weighted mass spectrum peaks in the vicinity of m(b) = 10(9.2) M. with a reasonable fit to the Schecter luminosity function if the baryon mass to blue light ratio is approximately 4. Overall, the simulations provide strong support for the CDM scenario. Of particular interest is that, while the baryons are not biased on scales greater-than-or-equal-to 1h-1 Mpc, the "galaxies" are, and that the "galaxies" have a correlation function of the required slope and the correct amplitude.
