Due to recent bot attacks, newly registered users are required to send a message via our contact form in order to be able to post in the forum. OpenLB – Open Source Lattice Boltzmann Code › Forums › on OpenLB › General Topics › Concentration fields in openLB › Reply To: Concentration fields in openLB July 22, 2024 at 8:30 pm #8990 shotaParticipant Simply, call the coupling operator every n-th time step using if(iT%n == 0) or something alike.