What is the Convergence index and how is it computed?
The convergence index is defined as: where: CI is the convergence index, EF is the computed error norm (such as the matrix residual or flux balance disparity) for the variable F, e is the convergence criterion controlled by the CONVergence command. fN is the normalizing factor, and CI is a normalized measure of convergence of the solution and has a value of unity when the error norm in the solution is equal to the product of the normalizing factor and the specified convergence criterion. By default EF is set equal to mass flow disparity in the computational domain (see FLUX command). This can be changed to be the appropriate error norm for any of the variables by the CONVergence command with the REFErence modifier. For PORFLOW and TIDAL, fN is always set to unity. For ANSWER fN is set equal to the incoming mass flow rate if the error norm is based on mass flow and the mass inflow is non-zero; otherwise it is set equal to unity. It should be noted that the default option in ANSWER is to
