Lately, I worked on a study about the 4 orientations of fin heat sink. Simulation and measurements match in 3 orientations (fin facing up, fin facing down and fin is parallel to the air flow). But twhen the fin is perpendicular to the air flow, the resutls are strange. Simluation has 87.9 deg.C and mesurement is 75.4 deg.C. I guess that orientation has more effect on radiation and convection in the measurement. Is it correct?