CFD approach to resistance prediction as a function of roughness

This paper aims to present a CFD approach to predict the resistance as a function of surface roughness by performing CFD simulations of towing tests of coated flat plates. Following a brief description of roughness and the roughness effect on flow and the turbulent boundary layer, the methodology of determination of the most suitable roughness function model to be used in the software is discussed in details. Next, the CFD approaches to represent smooth and rough velocity profile are presented . Finally, a new roughness function model is suggested and employed in the CFD software while a case study is performed to obtain the frictional resistance coefficients (CF ) of coated flat plates using the modified CFD approach. The results of the new approach show a very good agreement with the experimental data and it is shown that the new approach is able to predict the resistance of ship coatings as a function of roughness height