This model tests the inverse formulation of the flow functions.
The pressure difference dp and dpCalc
need to be equal up to the solver tolerance, except for a small
neighborhood around the origin. In this neighborhood around the
origin, the functions
Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_dp and
Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_m_flow
are not invertible.