Trans RINA, Vol 161, Part A4, Intl J Maritime Eng, Oct-Dec 2019


during servicing. It is worth mentioning that the increased fuel consumption and reduced speed are due to increased frictional resistance, which is the result of changes in the hull and propeller roughness and the physical conditions of the marine environment. In the presented study, two methods are applied to evaluate drag force of SALINA in both laden and ballast conditions. Details of the specifications are presented in Table 1 and Figure 1. In order to validate the obtained findings, the results of numerical simulation and experimental model have been compared. The results of the present study are generalizable to not only the SALINA but also to three similar oil tankers in the fleet of National Iranian Tanker Company.


Furthermore, after the disaster of the MT. Sanchi (one of the four tankers similar to the SALINA) in the China Sea, the results of this study could be a prelude to the initiation of scientific research on numerical simulation of the physical effect of the sea environment on maneuverability, engine, body movements, and interaction of the cargo and tanks of the MT. Sanchi before and after the collision, resulted in its explosion and sinking.


Table 1. Specifications of SALINA Year of built


Length Overall


Breadth (Extreme) Designed draft


Summer deadweight


displacement in summer draft Engine power (M.C.R.) Service speed


2009


274.18 m 50 m


17.023 m


164040 MT. 189187 MT. 18660 KW. 15.40 Knots


Figure 3. Corrected geometry of SALINA 2.1


GOVERNING EQUATIONS


Figure 1. SALINA (EX. MT. Sarv) 2.


The equations governing the fluid flow field are the same as Navier-Stokes equations. It is very challenging to directly solve the turbulent flows due to the effect of their disordered circular motions. In response to the mentioned difficulty, the averaged Navier-Stokes equations (RANS) were used, which are presented as equations 1 and 2 (White, 2015):


PRINCIPLES AND METHODS


The experimental model of this tanker at a scale of 1:100 and in accordance with the International Towing Tank Conference


In this study, an unstructured integrated grid was generated in the entire solution field using the CFX software. Required corrections on the vessel geometry were performed and its quality was confirmed


A-460 guidelines was constructed. The


specifications of the model are presented in Table 2 and Figure 2.


̅ = 0


+ ̅̅̅̅̅̅̅ ̅


= −1





+


{ ( ̅





+ ̅





)}− ́ ́ ̅̅̅̅̅̅̅


(1) + (2)


In these equations, the Reynolds stress (́ ́̅̅̅̅̅̅ ) was added to the equations. In this study, the k-ε turbulence model was used to model Reynolds stress in the averaged equations of Navier Stokes. The turbulence model k-ε uses empirical functions to model the near-wall boundary layers. At the maximum true speed of the vessel (16.5


©2019: The Royal Institution of Naval Architects


(Figure. 3). The next steps included generating solution fields, creating a computational grid and improving its quality, entering the prepared computational grid to the pre-processing section for modeling, and eventually extracting results in the post-processing section.


Table 2. Dimensions of experimental model of SALINA Length (mm) 2741


Width (mm) 500


Height (mm) 230


Draft (mm) 170


Figure 2. Painted and scaled model of the SALINA


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