I have a reach that is divided into three parts. the first part is in 1D that flows into a 2D area and this 2D area is connected at the downstream end to another 1D reach. the model fails to run also and I've tried many things like reducing the timestep for computation, adding pilot channels in the 1D reach, change tolerance in 1D/2D options. the error found is usually at the connection between 1D and 2D. Any suggestions on how I can improve this connection or edit anything else in the unsteady flow editor to make the model work?
you probably need a warm up period to help stabilize the model. It could also be that the location of the 1D/2D connection is not 1D in nature and probably not the best place to do the split. If the wse between the 1D and 2D can't match very well then you need to find a better spot.
there should be red dots pointing out where that errors possibly is. otherwise you will have to scan the boundary of the mesh to find the location. It is most likely at a sharp face of the mesh boundary. In some cases you can use Mapper to fix it by right clicking on the 2D Mesh in the tree and selecting fix mesh.