What is Nays2DFlood?

Nays2DFlood is a flood flow solver developed by Professor Yasuyuki Shimizu and his students from the University of Hokkaido along with several colleagues at CERI. The solver treats unsteady 2-dimensional plane flow using general curvilinear coordinates. This coordinate system allows both channel banks and floodplain edges to be fitted to the coordinate system. The solver adopts the computational scheme of the Nays2DH Solver developed by Professor Shimizu including the CIP momentum advection method, which maintain sharp flow gradients without numerical diffusion even in complex flow domains.

The solver enables the user to easily set the inflow conditions of an arbitrary number of inflow rivers that enter from the upstream end or sides of a river/floodplain complex.  Nay2dFloodhas been applied for flood flow analysis of rivers over a wide range of length scales, from small streams to the Mississippi. Because the solver does not require river channel data for large floods (where in-channel conveyance is a small part of the flood discharge), it can also used for extreme flood analysis in primitive rivers and rivers in developing countries, where channel bathymetric data is typically unavailable.