I am running a system model in Dymola (commercial model-based software). The model relates to heat and mass transfer from a porous substance during forced convection. My problem in asking this question is related to errors that occur while modeling the model.
With the current settings of the model, the specified simulation time (7200 sec.) Is successfully performed. But it generates the following prompts in the log file (intermittently throughout the run time):
ERROR: Failed to solve non-linear system using Newton solver. To get more information: Turn on Simulation/Setup/Debug/Nonlinear solver diagnostics/Details Solution to systems of equations not found at time = 882.457 Nonlinear system of equations number = 4 Infinity-norm of residue = 154.849 Iteration is not making good progress. Accumulated number of residue calculations: 25279 Last values of solution vector: drum.T_e = 306.346 drum.X_e = 0.0413446 Last values of residual vector: { -0.000157014, 154.849 }
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Failed to evaluate model for ODE-Jacobian Too many slow iterations with no progress Line search: DX-norm scaled-residua-norm residual (unscaled) Search direction{ -0.000634251, 6.52346E-006 } To investigate the properties of the function, you can plot the function in the search direction by pasting the following commands in the Dymola command window: Amat={<...>}; plotArray(Amat[:,1],Amat[:,2],-1); If the graph has discontinuities, local minima above zero, and/or knees this explains the problem.
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