Gustavsen A., Kohler C., Arasteh D., Curcuja D.
Bibliographic info:
Ashrae 2005 Winter meeting, technical and symposium papers, Orlando, February 2005

This paper uses computational fluid dynamics (FD) modeling to assess the accuracy of the simplified frame cavity conduction/convection models presented in ISO 15099 and used in software for rating and labeling window products. Three representative complex cavity cross-section profiles with varying dimensions and aspect ratios are examined. The results presented support the ISO 15099 rule that complex cavities with small throats should be subdivided, however, our data suggest that cavities with throats smaller than 7 mm should be subdivided, in contrast to the ISO 15099 rule, which places the break point at 5 mm. The results presented are for horizontal frame members because convection in vertical jambs involves very different aspect ratios that require three-dimensional CFD simulations.