OpenLB – Open Source Lattice Boltzmann Code › Forums › on OpenLB › Bug Reports › Incorrect geometry creation – forward-facing 2D step › Reply To: Incorrect geometry creation – forward-facing 2D step September 17, 2020 at 7:51 pm #5134 AdrianKeymaster Happy to help. As a sidenote: Your solution is basically the same as what is done in my patch – *(channel-step) is just a shorthand for wrapping the subtracted indicators in an identity.