Do the interpolation schemes used by HAMMER satisfy the Courant stability condition?
Courant stability criterion is not relevant to the method of characteristics (MOC), but rather applies to explicit finite-difference solutions of hyperbolic partial differential equations. (The Courant condition imposes a maximum time step as a function of the spatial step and wave speed.) In MOC, there is no theoretical limit on the size of the time step for the sake of stability; practical limits arise on account of accuracy concerns due to complex boundary conditions at nodes and nonlinear frictional losses.
Numerical method used for transient simulations in HAMMER