An investigation into the effect of biofouling on the ship hydrodynamic characteristics using CFD

Abstract

To reduce the fuel consumption and greenhouse gas emissions of ships, it is necessary to understand the ship resistance. In this context, understanding the effect of surface roughness on the frictional resistance is of particular importance since the skin friction, which often takes a large portion in ship drag, increases with surface roughness. Although a large number of studies have been carried out since the age of William Froude, understanding the roughness effect is yet challenging due to its unique feature in scaling. In this study, a Computational Fluid Dynamics (CFD) based unsteady Reynolds Averaged Navier-Stokes (RANS) resistance simulation model was developed to predict the effect of barnacle fouling mainly on the resistance and hull wake characteristics of the full-scale KRISO container ship (KCS) hull. Initially, a roughness function model was employed in the wallfunction of the CFD software to represent the surface conditions of barnacle fouling. A validation study was carried out involving the model-scale flat plate simulation, and then the same approach was applied in full-scale flat plate simulation and full-scale 3D KCS hull simulation for predicting the effect of barnacle fouling. The increase in frictional resistance due to the different fouling conditions were predicted and compared with the results obtained using the boundary layer similarity law analysis of Granville. Also, a further investigation of the roughness effect on the residuary resistance, viscous pressure resistance and wave making resistance was carried out. Finally, the roughness effect on the wave profile, pressure distribution along the hull, velocity distribution around the hull and wake flows were examined.

Comparative Study of Air Resistance with and without a Superstructure on a Container Ship Using Numerical Simulation

“…To analyze the effects of the presence or absence of superstructures on the resistance, the resistance performance of the full-scale ship was estimated using Equations (1)- (5). Here, C AA obtained from Equation (5) was calculated using the coefficient in Table 5, for the case without the superstructure and C AA was set to 0, when the superstructure was considered.…”

“…This indicated that calculation using an empirical formula could lead to over-estimation of the resistance performance of a full-scale ship, compared to a direct numerical interpretation, when considering the superstructures. To analyze the effects of the presence or absence of superstructures on the resistance, the resistance performance of the full-scale ship was estimated using Equations (1)- (5). Here, obtained from Equation (5) was calculated using the coefficient in Table 5, for the case without the superstructure and was set to 0, when the superstructure was considered.…”

“…Here, C AA was calculated using the method proposed by Kristensen and Lützen [17], which is shown in Equation (10). The ITTC value was the counter-calculated value of C DA , using Equation (5). The value of 0.67 calculated by the Fujiwara formula was the same result as the C DA value of the 6800 TEU-class container ship, with containers in the laden condition, provided by ITTC [19].…”

“…Since then, the analysis methods have evolved to consider other aspects, such as the free surface and variation in the ship's attitude for accurate performance estimation. In addition, full-scale numerical simulation [1][2][3] of a ship, which is difficult to perform with the latest experimental methods, numerical simulation considering the hull roughness [4,5], and various other studies are underway.…”

The Turbulent Boundary Layer and Frictional Drag Characteristics of New Generation Marine Fouling Control Coatings

“…[23] simulates the flat plate experiments of [17] for antifouling coated surfaces by adopting the roughness scale given in the experimental work to the wall functions in order to calculate the The turbulent boundary layer and frictional drag characteristics Burcu Erbaş of new generation marine fouling control coatings encountered frictional resistance difference by using CFD. Whilst, in [24] and [25] the effect of marine coatings, biofilm and barnacle fouling on frictional and wave resistance of a fullscale ship is predicted by using (Reynolds Averaged Navier Stokes (RANS) modelling. [26] presents CFD simulations in order to predict the effect of biofilm on the ship resistance by using the effective roughness length scale of [27] for biofilm along with developing a relevant roughness function to implement within wall functions.…”