3rd kind boundary condition and large river

Hi,

I have a large river in the middle of my model (about 100 m large), I want to use 3rd kind boundary condition for this river, but I can only place (automaticaly) the boundary condition on the two edges of the river and I have node in the middle of the river area.

But I think I have to put this condition too inside the river area.  Then I don't know how  to do? ???

Have I to construct meshes using other lines inside the river area in order to align  nodes and to be able to put the 3rd kind boundary condition in all the river area???

If someone can help me, suggestions are welcome

Have a nice day

Currently indeed there is no joining option for polygons in the boundary condition editor. One option would be to create a zig-zag line inside the river. Other options include putting the bc manually, by using a line in the middle of the river and a higher snap distance (assuming the the width of the river is more or less constant), and exporting all the FEFLOW nodes to a GIS format, clipping the ones in the river and importing them back as a BC.

Thank you for the answer Peter.  one precision, If I undertsand it correctly I need to do that all nodes are interconnected in the river with the BC (bold lines)?

regards