PURPOSE: To shorten calculation time and to reduce a storage capacity by dividing the whole of an area into areas and reducing the dimensions to analyze the areas in the case of areas which can be approximated to lower dimensions.

CONSTITUTION: With respect to formation of a compression wave due to, for example, plunge of a vehicle into a tunnel, its propagation, and analysis of its discharge to a tunnel exit shell, an area 31 is an entrance area until the vehicle plunges into a tunnel, and an area 32 in an area around the vehicle. The compression wave is generated when the vehicle included in the area 32 plunges into the tunnel. The compression wave is generated three-dimensionally; and when the vehicle velocity is smaller than the acoustic velocity, the compression wave proceeds in the tunnel more quickly than the vehicle because the compression wave proceeds forward at the acoustic velocity. Since the compression wave proceeding in the tunnel can be approximated as a one-dimensional phenomenon, a tunnel area 33 can be subjected to one-dimensional analysis. As the result, the storage capacity is made smaller and the calculation time is reduced in comparison with those for three-dimensional analysis of all of areas.