Using HVAC namelist for tunnel boundary conditions in the green line of the tel aviv LRT

The Green Line of the Tel Aviv light rail train is an ongoing project that will connect 4 municipalities. Though most of the line passes above ground, 4 stations and about 4 km of twin bore tunnels, pass underground. As part of the detailed design of the underground tunnels and stations, CFD analysis is being performed for both tunnels and stations.

One of the most challenging aspects of an underground tunnel or station, are the simulations boundary conditions. To obtain boundary conditions that reflect the changing pressure field, HVAC ducts and nodes were used as a means of coupling 1D calculations to 3D simulations.

The simulations encountered some numerical instabilities and severe access violations. But after refining the simulated geometry and settings, a reactive and realistic pressure field was obtained, allowing for better design of the tunnels and stations smoke control systems.