abstract:This paper deals with the optimum spacings of longitudinal fin arrays in forced convection theoretically. Four different fins in arrays such as rectangular, convex-parabolic, triangular, and concave-parabolic fins are taken into consideration in the analysis. The aspect ratio, interfin spacing, and heat transfer characteristics of the optimized fin arrays are investigated with given geometry of base plate, total fin volume, and transverse Biot number. A comparison in the total heat duties and overall surface efficiencies of the four different arrays is also made. All the results are presented in dimensionless forms for the convenience of parametric study and design analysis.