Frequently Asked Questions

Why does my model not initialize properly?

In case of problems with initialization of the model or the behavior of the system during the first seconds of a simulation, investigate selected initial conditions and the behavior of the system variables. Issues are often due to bad pressure initialization or rapid changes of pressure in reactors. Make sure to always define pressure start values to give a pressure gradient through the system. The pressure gradient ensures that we have a well defined (positive) flow direction during the first seconds of a simulation.

Why is the simulation so slow?

The simulation speed is affected if some states of the model limit the step size (possibly due to fast transients). The debug tools of your simulation environment can be used for further investigation of these issues. Slow simulation speed may also be due to large nonlinear systems of equations. Try to split nonlinear systems of equations by alternating volume and flow resistance models.