First three columns show 1D radial profiles of the rest-mass density, of the radial component of the four-velocity, and of the gas pressure on the equatorial plane in the Michel solution test in Boyer-Lindquist (upper) and Kerr-Schild coordinates (lower). The semianalytic solution is shown in red. This solution serves as initial condition, while the numerical results at t = 100 M are reported with blue circles. The fourth column shows the entropy increase normalised to the specific heat at constant volume, Δs/c_v, from t = 0 M to t = 100 M using each coordinate system. A smaller entropy change is related to a better preservation of the stationary solution.