A CFD problem is coupled to a transport (of, e.g., a chemistry species) in a uni-directional way.


We model a two-dimensional incompressible fluid flowing through a channel with an obstacle. The fluid problem is coupled to a simple transport problem in a uni-directional fashion. The transport problem is initialized with a circular blob close to the inflow. The density of the species is denoted with T (like temperature). The convected and diffused blob after 23 timesteps:

Flap setup

The behavior of the blob over the full 200 timesteps looks as follows:

Available solvers

Fluid participant:

Transport participant:

Running the simulation

Open two separate terminals and start one fluid and one transport participant by calling the respective run scripts run.sh located in each of the participants’ directory. For example:

cd fluid-nutils


cd transport-nutils


All solvers generate vtk files which can be visualized using, e.g., ParaView.