Abstract Earlier investigations have determined the forced-convection heat transfer of a single isolated plane or cylinder and of continuous parallel fins. This paper presents test results for groups of small discontinuous fins and pins. These results have been correlated on the basis of Reynolds number in order to show a common quantitative relationship. The heat-transfer coefficients are found to increase in substantially inverse proportion to the square root of the size, or perimeter of the surface element, and can be more than doubled, compared to continuous fins. The relationship between heat transfer and fluid friction is covered quantitatively. Tests of applications show that the data may be rationally applied with satisfactory results.