User Controllable Level of Detail Abstraction System
Summary of technology
Building Information Modelling (BIM) is steadily superseding traditional CAD modelling, adding extra intelligence to 3D models through associated databases of information which can enable, for example, automated clash detection and quantity take-offs for activity-based costing systems.
Because a BIM contains objects instead of just lines, and those objects contain information on what their purpose is, BIM software is able to automatically detect clashes between walls, support structures, plumbing and equipment, allowing for changes at the design stage rather than at the more costly build stage. Similarly, the stored data on what materials objects are made from allows for automatic calculation of required materials, allowing for automated scheduling to help ensure the right quantities of material are available just in time, saving on inventory tracking and storage requirements. These abilities and others enabled by BIM are leading to large savings on projects of all sizes and driving industry uptake.
Computational Fluid Dynamics (CFD) is a powerful method of modelling fire safety, mechanical stress and wind flows around buildings. However importing models from BIM or CAD systems to CFD packages can be problematic due to the size and complexity of the models, meaning the import process and CFD run times can be unacceptably slow for complex or large models, for example LNG trains. The model will also typically require a large amount of manual adjustment to be made CFD simulation-ready, a time intensive prospect.
The Level of Detail Abstraction System (LODAS) technology overcomes this problem by abstracting the base BIM model using two distinct methods: simplification and cubification, such that the integrity of the model is maintained for CFD purposes, but the data has been reduced in size sufficiently for the CFD package performance to be acceptable. By providing a selection of abstraction methods and user control over what level of detail to keep, the LODAS system allows the user to determine what level of abstraction is acceptable or necessary and quickly produce models for use in CFD simulation, or for any other task where a reduced level of detail is desirable.
The advantages of this approach are:
- The user can control the level of simplification of the BIM data, and there are a number of options as to how the simplification is undertaken, so that the CFD model is still a valid proxy for fluid modelling purposes.
- The increased speed of BIM to CFD conversion means that CFD can make a an effective contribution to the overall design process.
Stuart Porter from the Department of Chemical Engineering at Curtin University has developed this technique as part of his PhD thesis.
Stage of development
The concept has been implemented as a plugin for the AutoCAD Architecture software package, producing file formats which can be imported by the ANSYS Fluent CFD Package. It has been tested with a range of relatively simple structures, reducing CFD run times by a factor of 30 while showing comparable fluid flows around the structures.
The software is unpublished and a trade secret, and is potentially patentable.
We are looking for a software vendor to collaborate on more extensive testing with a view to licensing the technology to integrate into their product suite.