Jabarkan Untuk aliran permukaan bebas: dari Persamaan faktor gesekan Darcy

Colebrook, C. F. and White, C. M. (1937). "Experiments with Fluid Friction in Roughened Pipes". Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences

Moody, L.F. (1944). "Friction Factors for Pipe Flow". Transactions of the ASME