New to LBM and OpenLB? Attend our upcoming one-week hands-on Spring School in Heidelberg/Germany in March 2024 OpenLB – Open Source Lattice Boltzmann Code › Forums › on Lattice Boltzmann Methods › General Topics › Permeability Calculation Poiseuille › Reply To: Permeability Calculation Poiseuille April 24, 2019 at 9:02 am #4263 fkParticipant Dear Ladasicr, could you post the code of how you set the boundary conditions here? My guess is, that you do not have a smooth start up and this is why the simulation blows up. Best, Fabian