Previously, to simulate the mean age of air the user had to define a passive scalar source. This has now been simplified for the user. Under Results control → Field calculations → Mean age of fluid you can find the settings for this output (see image below). This field calculation is available in the incompressible, convective heat transfer, and conjugate heat transfer v2.0.
In the next step, you must set the turbulent Schmidt number and the diffusion coefficient (shown in the image below).
The default value provided for the diffusion coefficient is 2.88 \times 10^{-5} \mathrm{m/s}^2 which is recommended for turbulent air flows (Abanto et al 2003). For water, we recommend you use 2.299 \times 10^{-9} \mathrm{m/s}^2 (Holz et al 2000). For the turbulent Schmidt number, we recommend using a value between 07. and 0.9 (Tominaga et al 2007). In the post-processing, you can visualize how long the air has been inside the system or room which directly tells you how well a room is ventilated. This can be very valuable for applications in Covid mitigation