Setting boundary conditions for 3D CFD calculations based on 1D and 2D hydrodynamic models. The case of a hydraulic diversion-overflow work in Profitis Daniil Stream in Athens, Greece.

We performed steady state calculations in Profitis Daniil Stream, an important component of the combined sewerage system of Athens. We employed the Standard Step Method (SSM), 1D HEC-RAS and TELEMAC-2D to define the boundary conditions, mainly water depths, of a 3D CFD model that is used to optimize the design of a diversion work. As expected, water depths predicted by SSM and 1D HEC-RAS coincide; also, these are generally close to TELEMAC-2D calculations for turbulent viscosity values in the range of 0.005 m2 s-1 with the exception of regions with changing bottom slope, where water surface is more accurately predicted by TELEMAC-2D. Thus, we can use 1D approaches to define water depths as boundary conditions in regions without significant bottom slope changes; otherwise, we need to use TELEMAC-2D with proper viscosity values that additionally provides a realistic depth-average velocity profile, when required.     «

We performed steady state calculations in Profitis Daniil Stream, an important component of the combined sewerage system of Athens. We employed the Standard Step Method (SSM), 1D HEC-RAS and TELEMAC-2D to define the boundary conditions, mainly water depths, of a 3D CFD model that is used to optimize the design of a diversion work. As expected, water depths predicted by SSM and 1D HEC-RAS coincide; also, these are generally close to TELEMAC-2D calculations for turbulent viscosity values in the r...     »