| In ship design, it is very important to predict the resistance and viscous flow around surface ship accurately. For a long time, people divide total resistance into viscous resistance and wave resistance independently. Namely, potential theory method is used to solve free-surface problem and get wave resistance. However, it ignores the influence of viscosity, which cann't give the details of the wake distribution and stern waves. With the rapid development of computers, computational fluid dynamics methods have changed deep at computing power and practical use. It can be better used in calculating resistance and simulating viscous problem. In this paper, viscous flow around different kinds of surface ship models moving ahead is solved by using the RANS equations, which include typical surface singal hulls, catamaran and trimaran. The predicted resistance coefficients and wave profiles along ship hull agree well with the measured results. Also viscous flow field details are given. The specific process is as follows:Firstly, the viscous flow around the Wigley mathematical hull moving ahead is solved by using the RANS equations based on the PISO (Pressure Implicit with Splitting of Operators) scheme and the SST k ? ? turbulence model. The free surface is simulated with single phase Level set method. The values of drag coefficient and the wave profile obtained by the presented method are in good agreement with the experimental data, which verifies the reliability of the presented algorithm and provides some experience for the free surface flow simulation of the other complex ships.Secondly, the flow of the other two typical standard surface ship (DTMB 5415 hull and Series 60 hull ) is simulated by the same method. For DTMB 5415 hull, the values of drag coefficient and the wave profile obtained are in good agreement with the experimental datas, also the important characteristics of wake distribution are captured accurately. For Series 60 hull, we not only get the good drag coefficients of a series of speeds, but also give the details of the flow field (such as the distribution of velocity, pressure and the eddy viscosity).Thirdly, considering the difficulties of generating structural grids for mult-hulls, the overlapping grids (overset) technology is introduced. And then, taking Wigley as example, the resistance and viscous flow around high speed catamaran and trimaran models moving ahead are numerically simulated, based on the basic theory and algorithms above:To the high speed catamaran, the choice of ship form, design speed and hull separation will influence the performance of catamaran. In this thesis,the latter two factors are considered to study the resistance properties of catamaran. Total resistance of the catamaran is compared with the two singal hulls, and wave interference between two hulls is analysed by drawing the residual resistance coefficient curves, capturing the wave profiles and wave contours. Also, the flow field details in typical layout of catamaran are given, providing reference values for the design of high speed catamaran.To the high speed trimaran, the symmetry, the displacement and the position of side hulls, the ship form of main hull and side hulls are the factors influencing the performance of trimaran. In this thesis, the position of the side-hull related to the main hull is considered to study the resistance properties of trimaran. By changing the horizontal and vertical offsets of the side-hull, the resistance coefficients with a series of Froude numbers between 0.3 and 0.7 are calculated, which gives the conclusion that there's no same best position of the side-hulls for all Froude numbers. For the higher Froude number, wave interference between the main-hull and side-hull is small when the side-hull is placed at the back and near the main-hull. Also, we give the flow field details of trimaran under the best position when Froude number is 0.6.Finally, by summarizing the results, we can see that the research is helpful to prediction for hydrodynamic performance and the better choice of design speed and hull separation and so on.
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