Pages 45-49
Flow fields around hybrid hulls at high speed have two special features. One is the strongly non-linear phenomena such as spray, ventilation, cavitation, and so on. The other is the interaction among hull components. Firstly in this paper, a submerged body with surface-piercing struts in tandem is considered. A flow field around the hull was simulated by a finite-difference method for the Euler equations with non-linear free surface conditons. The algorithm is based on the MAC method. Since a free surface configuration is expressed by the single-value wave height function, spray cannot be simulated. Ventilation and cavitaion are not also considered in this scheme. The interactions of waves generated by a submerged body and two struts, however, are expressed. Results simulated agree well with experimental data. Secondly, a submerged body with hydrofoils and surface-piercing struts in tandem is considered. The method of calculation is same as that of the former. Computed lifts generated by hydrofoils are compared with the experimental data. Although the agreement is not so well for the aft foil, we got a good agreement for the fore foil. It is not well. The reasons for the disagreement for the aft foil are (1) neglect of the viscosity, ,i.e., viscous wake due to the fore foil is not considered, (2) inconsideration of spray, (3) coarse computational grid and so on. A modelling of high speed flow phenomena and the development of the accurate solver remain as future problems.
