I pick this thread from one of my recent experiences. Typically, first order advection schemes (ADV1) and second order accurate advection schemes (ADV5) would produce different results because of artificial viscosity in ADV1. But would these results be very much affected ONLY while simulating distributed resistance, which models a negative pressure gradient zone? Or do these schemes always produce significantly different results for ALL types of physics, viz. incompressible turbulent flow, heat transfer, compressible flow etc.?
We would recommend switching away from ADV1 and to ADV5 for many purposes now. Standard incompressible flow should be OK but ADV5 will be better for compressible and pressure driven flows, those with resistances as you rightly say and also for many heat transfer calculations now too.
Product Support Specialist