# Visualisation of airflow network calculation convergence in E+?

Hello,

Sometimes my airflow network calculations converge, but most of the time they don't. And it doesn't seem to make sense to me. I must admit that I altered some components in the source code, but I don't think they cause the problem.

Does anyone know a way to visualise the residuals in an energyplus airflow network calculation? ( Or to save the iteration steps to a textfile. )

Thanks!

Could you be more specific about your modifications?

Hi Jason, sure. I created a self-regulating vent component that limits the flow through the vent when a maximum dP value is reached. In the cases that do converge this component seems to be working. I am also in the process of creating an advanced hybrid ventilation manager. However the calculations don't reach the point where this is called, so that can't be the problem. I suppose the Newton-Raphson algorithm is not converging because the initial guess is too far away from the solution. By looking at the residuals I hope to get a better insight.

If that is what you are doing, then I wouldn't be too sure that your modifications are not the problem. It depends on exactly how you've changed things, but it could (effectively) decouple parts of the flow network in a way that the solver does not expect. But good luck!