Models of expanding spherical HII regions are considered. The full system of equations used by Goldworthy (1961) in his discussion on the large scale flow are solved numerically without making any of his assumptions, using artificial viscosity method. All three types of ionization fronts (Weak R-Type, Strong D-Type and Weak D-Type) are obtained for the cases when the initial density is uniform in HI region and also when it is decreasing exponentially.