OpenLB – Open Source Lattice Boltzmann Code › Forums › on OpenLB › General Topics › Multicomponent flow › Reply To: Multicomponent flow June 9, 2021 at 9:43 am #5721 stephanModerator It is hard to tell what exactly triggers the divergence. The two lines of code you included simply refer to (as the name tells) analytical constants set in your program. Dependent on what for (and also how) you use them, instability occurs.