Aerodynamic Equilibrium and Stability in Ventilation and Air Quality Control of Complex Urban Tunnels
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2019-03-10
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Alternative Title:Aerodynamic Equilibrium and Stability for Air Quality Management in Complex Urban Tunnels
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Edition:Final Report, Start date: 11/01/2017 End date: 12/31/2018
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Abstract:Modern urban vehicular tunnels generally have a branched structure and complex nonlinear aerodynamics. The authors established and analyzed the 1-D aerodynamic equations and pollutant dispersion model in such bifurcate hydraulic networks. To design a tractable model that captures system complexity, the authors proposed a novel piecewise-affine (PWA) approximation for the flow-dependent local pressure-loss coefficients at tunnel junctions. This enables them to model the flow system via first-order ordinary differential equations (ODEs) with piecewise-quadratic polynomials. The authors proved a fundamental and easily verifiable sufficient condition for the uniqueness and stability of the steady-state solution of each ODE piece. The authors also demonstrated via a numerical study that for the entire system (across different ODE pieces) there may exist multiple stable steady-state solutions, which can lead to different CO concentration distributions in the system. This study provides a systematic modeling tool and a theoretical foundation for air quality management in complex tunnels.
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