variavel0=<b>MARCELO ANDREOTTI</b> - marcelo-andreotti@bol.com.br UNB
<b>FRANCISCO RICARDO DA CUNHA</b> - frcunha@unb.br UNB
<b>ALDO JOĂO DE SOUSA</b> - aldo@unb.br UNB
<b>Abstract.</b> In this work is developed a study about drag reduction in tubulents flow. This effect of decreasing the friction factor of the flow, can be obtained by the addition of fibers or high molecular weight polymers that cause a viscosity stress anisotropy, decreasing the efficiency of transport of momentum by turbulent flutuations. The present analysis is done based on a non-linear constitutive model which takes in to account an extra deformation rate of the flow in the direction of additive local orientation. The model is applied for developing an extension of Kárman-Prandtl friction theory with the objective of investigating the first effect of the additives on the flow. The results predict by the theoretical model were adjusted by means of experimental data, showing a reduction of 65% of the friction factor of the flow for a concentration of 350 ppm of polyacrylamide.
<b>Keywords.</b> DRAG REDUCTION, POLIMERS, FIBERS.