How does AcuSolve compute the residual ratios and solution ratios that are used to check for convergence? in Altair AcuSolve Posted July 31, 2013 · Report reply The residual ratios used by AcuSolve are a non-dimensional measure of how "out-of-balance" the governing equations are. The residual ratios are recomputed at each timestep to give an indication of how well the solution is converging.The solution ratio that is computed by AcuSolve represents the ratio of the change in the solution between timesteps to the solution at the previous timestep. This value indicates the level of unsteadiness present in the solution.Note that the solution ratios and residual ratios are computed using the contribution of each node in the model. The single value is obtained by taking the appropriate norm of the contribution from each node. The details of this procedure are described in the attached document.