The shipping industry play a vital role in the global economic exchanges. Bulbous bow optimization for ship is one of the ways to increase the efficiency of the ship through its hydrodynamic performance. Researches shows that by choosing the appropriate form of bulbous bow, it is possible to reduce the resistance of the vessel. However, few studies examine the effect of bulbous bow specially. furthermore, the design of the bulbous bow should be suitable for each vessel. Most of the previously studies were conducted experimentally, but all of the model could not be examined. Since they were cost and time consuming fortunately today the technological advancement and software development help us to use CFD method that leads simulating and examine different models without spending exorbitant costly. In this study, with the aim of STAR-CCM + software, the effects of changes in bulbous bow length on hydrodynamic behaviour, especially floating resistance
force, have been investigated using the CFD method for the KCS ship, the experimental results are available.
For this purpose, the length of the bulbous bow was reduced by 5%, 5%, 15% and 25% compared to the baseline, and then simulations were performed on three Froude numbers of 0.2209, 0.2599 and 0.2989. To check the validity of the results in the first step, numerical solution has been validated with the help of the experimental results. Their results of the simulations show that with reducing the bulbous bow length by 5%, the total resistance in the three landings mentioned increased by 0.05, 0.04 and 0.09%, respectively, but increased the length by 5%. %, 15% and 25% for three Froude numbers the total resistance reduced by 0.05, 0.04 and 0.09 in model C 0.18, 0.25 and 0.33 in model D and / 50, respectively. 0, 0.51 and 0.53E. Also, with increasing the Froud number, the role of the bulbous bow will be greater in rate the total resistance