Numerical analysis on pollutant dispersion in naturally ventilated buildings: nonisothermal conditions

Resumo

Pollutants dispersion and human exposure in urban areas are closely linked to urban and building
ventilation. In this sense, the main target of the present work is to study the pollutant dispersion phenomenon in
naturally ventilated buildings using a numerical model considering incompressible flows with heat and mass
transport. For the flow simulation, a semi-implicit Characteristic-Based Split (CBS) model is used in the context

of the Finite Element Method, where linear tetrahedral elements are used in spatial discretization. The Navier-
Stokes equations and the conservation equations for mass, energy and chemical species form the system of

fundamental equations for the flow field. Flow turbulence is treated through Large Eddy Simulation (LES),
where the Smagorinsky’s approach is adopted for subgrid scale modeling. Thermal effects on the flow field are
considered in the momentum balance equation through buoyancy forces, which are calculated taking into
account the Boussinesq’s approximation. Classic examples of Fluid Dynamics and Transport Phenomena are
analyzed to verify the numerical model proposed here and a numerical investigation is performed considering a
building model subject to natural ventilation, where pollutant dispersion and thermal effects are evaluated
simultaneously.