How CFD Simulation Impacts Design
The impact of CFD on AEC applications is directly related to the interpretation of simulation results; the ability to assess performance, identify opportunities for improvement, and quantify the impact of modification. Results visualization provides the opportunity to optimize design performance characteristics such as energy consumption, amount of contaminant entrained, thermal comfort, solar influence, hot air recirculation, and various other metrics of AEC application design performance.
CFD Impact on the Design Process
In the past, CFD was really only used by dedicated PhD analysts, with a “throw it over the wall” mentality from the design team. Since that time, advancements in both hardware and software interfaces have made the technology more practical.
Leveraging CFD simulation earlier in the design process allows potential performance issues to be corrected, eliminating costly rework or retrofitting later on. This is particularly the case in the AEC industry where many applications, such as buildings, are relatively large and impractical to prototype and test.
Classic Design Cycle
Many CFD consultants are contacted at Step 7 in a traditional design process when performance is not meeting specifications. Using CFD, they can determine the root cause of the issue, but implementing the fix can be expensive and require the space to be offline for the end client.
An AEC design cycle that does not implement CFD can lead to problems during the construction and initial start-up phase. These issues result in a cycle of expensive rework efforts, delays and downtime for the end client.
|7||Fail - Rework Required|
CFD Upfront Design Cycle
By contrast, when leveraging CFD early in the design cycle, potential problems can be addressed before construction.
|4||Engineering with CFD|
CFD Impact on AEC Applications
Controlling air flow is an important aspect of AEC design and has a direct impact on performance and energy conservation. A strong plume of cold inlet air directly over a cubicle can make the occupant uncomfortable. The hot exhaust from machinery or data servers can degrade cooling performance when it is allowed to recirculate back into the intakes. CFD results visualization is used to spot potential problems upfront and refine the location, size, and layout of system components.
In building design, significant energy is consumed by equipment which moves and conditions air. The amount of air and conditioning required can be optimized by assessing thermal stratification and air flow paths in CFD. Active, passive, and hybrid heating and cooling strategies can all be evaluated to determine the amount of energy consumed by a given design. A video discussing energy savings can be found here.
Contaminants, such as building or equipment exhaust, should be evacuated without re-entering the ventilation system, or in other words, without being entrained by the ventilation systems intake.
The design of systems for removing contaminated air from rooms or buildings should ensure that air intake systems are not configured to cause contaminant entrainment. CFD enables designers to visualize exhaust air and quantify the amount of exhaust entrained by intake systems. Interpretation of these results can impact design variables such as the location of supplies and returns, filter sizes and air exchange rates.
Human comfort is an influential consideration when developing a ventilation system. Design performance relating to air temperature, velocity, humidity, clothing, and metabolic rate can all be assessed in CFD to impact human comfort.
The ASHRAE definition of human thermal comfort can be found here in the help.
The sun provides Earth with energy that can influence the thermal performance of building design. Walls and rooftops absorb energy while windows absorb and transmit it into buildings. CFD helps designers understand the implications of solar radiation to either harness or block it. For more information, a solar heating tutorial is available here.