What is CFD?

Computational Fluid Dynamics (CFD) is the term used to describe a family of numerical methods used to calculate the temperature, velocity and various other fluid properties throughout a region of space.   

 CFD may be used to answer questions such as:

• What sort of temperature distribution could I expect throughout this atrium under clear sky summer conditions?
• Will the arrangement of supply diffusers provide adequate air movement?
• Is the location of the radiators going to provide good comfort conditions?
• What effect will the shape of the building have on local wind velocity?

DesignBuilder 3-D CFD

DesignBuilder CFD has been specifically designed to provide users with a tool that can be used to predict airflow and temperature distribution in and around buildings using the same methods as the general purpose pure CFD packages but at a fraction of the cost and without the need for any specialist knowledge.

Using conventional CFD packages for building airflow analysis can be a time consuming task requiring very careful attention to setting up the correct geometry and boundary conditions. Using CFD in DesignBuilder simplifies this process hugely by automatically providing the geometry and boundary conditions. Temperatures, heat flows and flow rates previously calculated by EnergyPlus can be seamlessly used to provide boundary conditions simply by specifying the time/date of the CFD analysis.

The CFD interface has been designed to enable virtual ‘push-button’ CFD analyses from automatically generated rule-based default data with options to allow more experienced or interested users to modify this data as required. Adopting this approach enables users to obtain realistic 3-D CFD analyses without having any specialist CFD knowledge.

Some of the key DesignBuilder CFD features:

• 3-D CFD grids are generated automatically from model geometry and boundary conditions using algorithms to promote optimal solution convergence.
• The CFD engine has been developed around the SIMPLER algorithm, which belongs to one of the most widely used families of CFD solution methods. Turbulence can be modelled using the widely researched and documented k-e model and there are plans to introduce additional models for specific applications.
• The interface incorporates tools to enable a wide range of boundary conditions such as supply diffusers, extracts, temperature patches, etc. to be assigned to room surfaces. A component library is also provided to enable radiators, fan-coil units, furniture, occupants, etc. to be located anywhere within the model and automatically incorporated within the analysis.
• Boundary conditions can be automatically assigned from a previous EnergyPlus simulation.
• 3-D CFD results are displayed using the DesignBuilder OpenGL graphics engine providing impressive, easy-to-interpret images and movies of velocity vectors, temperature contours, iso-surfaces, particle streams, etc.

  

Availability

A beta test version of DesignBuilder CFD will be made available in June 08 free to all existing and future DesignBuilder v.1 license holders. A 30-day free trial version will also be available. The CFD module will be released with DesignBuilder v.2.0.