This section covers the processes involved in running CFD calculations in DesignBuilder.
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 when applied to buildings can provide the designer with information on probable air velocities, pressures and temperatures that will occur at any point through a predefined air volume in and around building spaces. Boundary conditions are specified which may include the effects of climate, internal heat gains and HVAC systems. DesignBuilder CFD can be used for both external and internal analyses.
External CFD analysis provides the distribution of air velocity and pressure around building structures due to the wind effect and this information can be used to assess pedestrian comfort, determine local pressures for positioning HVAC intakes/exhausts and to calculate more accurate pressure coefficients for EnergyPlus calculated natural ventilation simulations.
Example External CFD Analysis Output - Wind Pressure Study
Internal CFD analysis provides information on the distribution of air velocity, pressure and temperature (and several other calculated parameters) throughout the inside of building spaces. Also calculated is 'age of air' to indicate the relative 'freshness' of the air through the domain and also a comfort index. This information can be used to assess the effectiveness of various HVAC and natural ventilation system designs and to evaluate consequent interior comfort conditions.
Example Internal CFD Analysis Output - Occupant Comfort