# Coupled Interface Boundary Condition for Multi-Region Solver

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 August 1, 2021, 14:09 Coupled Interface Boundary Condition for Multi-Region Solver #1 New Member   Saumava Dey Join Date: Sep 2020 Posts: 29 Rep Power: 3 Hello! I am developing a multi-region solver for coupling water flow over the overland surface and through stream networks using the diffusive model of Saint Venant equations. My simulation region consists of two regions: overland and channel. At the interface of the overland region, I need to exchange a flux with the channel region. The flux is one-way (overland to channel) or two-way (overland to channel and vice versa) based on a parameter Zb (bank elevation). The flux calculations are as follows: if (Zb > hc) Qoc = Cd*(ho - Zb)^1.5 Qco = 0 else Qoc = Qco = Cd*((ho - hc)^0.5)*(ho - Zb) ho = flow depth in the overland region hc = flow depth in the channel Cd = a constant Qoc = flux from overland to channel Qco = flux from channel to overland I seek help in how to implement it as a boundary condition on the coupled interface. I desperately need some help as my whole work has got stuck for some time due to this.

 Tags coupled bc, coupled boundary, multiregions