How were the current vent percentages in fruit clamshell packages derived?


I am interested in how the current vent percentages that are seen in various fruit clamshell packages were derived. I understand the purpose of the venting but I am wondering if the percentages used by the various manufacturers are based upon data or were something that they put in because they considered it to be “enough.” Would you have any idea about this?


Many studies have evaluated the ideal design and vent percentage. I typically use the rule of thumb that a clamshell package needs to have around 5% of the total area vented, as this offers a happy medium between proper air distribution for initial (pre)cooling, ideal temperature management, and appropriate mechanical strength.
New 3D computational flow dynamics modeling has offered alternative designs and allows us to visualize the appropriate air movement and pressure loss within different designs and packages. 
I recommend reading the article titled "Design of Packaging Vents for Cooling Fresh Horticultural Produce."
-Irwin R. Donis-Gonzalez