High-pressure gas injection into a low-pressure liquid pool with a free surface in cylindrical geometry with internals was numerically simulated using the computer code IVA2/005. Bubble formation and pressure history as a function of time were predicted and compared with the experimental observation for a 0.6-MPa pressure source. A comparison with the previous prediction of a 1.1-MPa pressure source experiment is made. Numerical diffusion and flow pattern prediction influence the gas propagation, which influences in turn the sharpness of the predicted bubble and water surface and the pressure history in time. The same geometry, but with a gas, was computationally simulated. The comparison proves that the code integrator works well without a constitutive package. Methods to measure the reduction of numerical diffusion are proposed. Comparison with the tree acoustic experiments shows that IVA2 can simulate pressure wave phenomena in two-phase two-component mixtures with strong nonhomogeneity.