OpenLB – Open Source Lattice Boltzmann Code › Forums › on OpenLB › General Topics › BounceBackVelocity › Reply To: BounceBackVelocity October 26, 2021 at 8:49 pm #6100 AdrianKeymaster This is most likely the same root cause (some mistake in application / compilation setup) as your other issue with setting up bouzidi boundaries. What happens if your write olb::setBounceBackVelocityBoundary?