Impact of biofilm on the resistance characteristics and nominal wake

Abstract

Numerical assessment of the impact of biofilm on the resistance characteristics and nominal wake is carried out within this study. Therefore, roughness function models are implemented within the wall function of the commercial software package. Extensive verification study as well as the estimation of numerical uncertainties in the prediction of the resistance characteristics and nominal wake is made. Furthermore, numerical uncertainties in the prediction of the change in resistance characteristics and nominal wake are assessed as well. Thereafter, validation study is carried out by comparing the obtained increases in the frictional and total resistance with the increases obtained using Granville similarity law scaling method. The significant impact of biofilm on the resistance characteristics as well as on the nominal wake is noted. Thus, total resistance and frictional resistance increase due to the presence of biofilm, while wave resistance decreases, contradicting the classical methods, which consider that only frictional resistance is affected due to the presence of roughness. Furthermore, nominal wake coefficient is increased due to the presence of biofilm, which causes slowdown of the flow.