Residual Monitoring for unsteady problem

James

Hello all. While modelling Pressure pulses travelling down a straigt pipe, I encountered inacurate propagation velocities and found that the best way to eliminate these was to use the Explicit Unsteady time formulation. However when doing this The residuas do not tend to converge but remain relatively constant. Could anyone shed some light on what the residuals are showing and how should I monitor solution accuracy. Thanks in advance for your help