In the course of the most recent thirty years reduction of ship resistance and saving fuel consumption to accomplish higher speed with reduction of pollutants has been the significant subject for researchers. Micro bubble drag reduction technique is the one of the most interesting thoughts in this field owing to its great advantages, such as considerable potential drag reduction, easy operations, environmental friendliness and low costs. In this study a 3-D numerical investigation into frictional drag reduction by air micro bubbles is applied on KRISO container ship model. The objective is to understand the mechanism of resistance reduction through micro bubbles injection under model ship at different Froude numbers, injection rate and of course volume fractions. The numerical simulations are performed using a commercial CFD code solving Reynolds averaged Navier-Stokes (RANS) equations. For more than 36 simulations has performed to investigate the effect of injection of micro bubble under ship model hull and to estimate the local Coefficient of friction values along ship hull model. The results show that at all of the examined Froude number, frictional resistance reduction attained but at different rates and a maximum drag reduction of 27.6 % obtained at 0.282 Froude number with 4.8 % air volume fraction. Keywords ship resistance • KRISO ship model • container ship • micro bubble • drag reduction • numerical simulation • ANSYS FLUENT Marine systems and ocean technology j o u r n a l manuscript No.

In the course of the most recent thirty years reduction of ship resistance and saving fuel consumption to accomplish higher speed with reduction of pollutants has been the significant subject for researchers. Micro bubble drag reduction technique is the one of the most interesting thoughts in this field owing to its great advantages, such as considerable potential drag reduction, easy operations, environmental friendliness and low costs. In this study a 3-D numerical investigation into frictional drag reduction by air micro bubbles is applied on KRISO container ship model. The objective is to understand the mechanism of resistance reduction through micro bubbles injection under model ship at different Froude numbers, injection rate and of course volume fractions. The numerical simulations are performed using a commercial CFD code solving Reynolds averaged Navier-Stokes (RANS) equations. For more than 36 simulations has performed to investigate the effect of injection of micro bubble under ship model hull and to estimate the local Coefficient of friction values along ship hull model. The results show that at all of the examined Froude number, frictional resistance reduction attained but at different rates and a maximum drag reduction of 27.6 % obtained at 0.282 Froude number with 4.8 % air volume fraction.