The evolution of the intergalactic medium (IGM) in a cold dark matter-dominated universe is studied. The dark matter is approximated as a pressureless ideal fluid while the IGM is approximated as an ordinary fluid. Several three-dimensional numerical simulations were carried out to trace the evolution of the model universe from z of about 100 to the present time. It is found that the growth of the rms density fluctuations in the IGM is greatly reduced during the period of heating, but it picks up at late times as gravity dominates again.
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