The Flow Resistance Factor Treated by the Maximum Entropy Principle

摘要

In the flow under pressure, through ducts whose roughness, diameter and length values are previously known, the knowledge of the equation of velocities distribution and the final behavior of the shear stress, presented in the flow, are fundamental in the understanding of the hydrodynamic laws present in this process. The evaluation of the distributed hydraulic load loss based on the universal formula of Darcy-Weisbach, whose attainment of the resistance factor "f" lies over a classic logarithm model of vertical profile of velocities distribution, from Karman-Prandtl, deserves special attention since this profile of velocities presents two conceptual inconsistencies: one in the wall of the pipe, where the model would have to represent null speed, and another one in the axle of the pipe, where the model would have to represent the null shear stress. For in such a way, the interest for a better representation of the factor of resistance based on the new model of distribution of velocities considered by Chiu (1993), from the Maximization of the Entropy consisted by the Theory of the Information, where the classic model restrictions do not appear, is opportune and encouraged the modeling work with the use of the adjustments already established by Nikuradse, resulting in one new analytical model for the "f" representation.