Difficulties with Obtuse-Angled Elements in Finite-Element Thermal Models

Thermal conductances are computed by finite-element techniques for typical triangular elements.. Heat-transfer rates computed with these conductances are compared to heat-transfer rates computed from exact, closed-form mathematical formulas and from refined models. The comparisons show that significant simulation errors can occur in triangular elements that have an internal angle greater than 90 degrees. An alternative, centroid method is shown to give smaller errors by some measures and in some cases but larger errors in most cases.