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Direct Generation of Cartesian Grid for As-built CFD Analysis from Laser Scanned Point Clouds

Introduction: In recent years, numerical simulation of heat and air flow in indoor spaces using 3-dimensional Computational Fluid Dynamics (3D CFD) has begun to spread in architecture and environmental engineering. For the 3D CFD analysis, currently it is necessary for engineers to build a 3D CAD model of a space to be analyzed, and then to generate a grid for the analysis from the CAD model. On the other hand, as the regulations of energy-saving efficiency in buildings have been strengthened and number of repair works of air conditioning equipment is increasing, the demand for “as-built” CFD analysis is also rapidly increasing where the heat and air flow inside indoor spaces in existing buildings have to modelled and analyzed to rationalize the repair works. Accordingly, CFD grids for as-built CFD analysis must be generated that reflect the existing geometries of an indoor space to be analyzed. However, timeconsuming manual operations are still required to measure the existing space, to build an accurate asbuilt 3D CAD model of the space, and to generate a CFD grids that fit with the CAD model. Even if a 3D laser scanner is introduced to improve measurement efficiency, it is substantially impossible to generate a complete as-built 3D CAD model of the existing spaces from the scanned point cloud in a fully automatic and stable manner.