Stena Teknik - OpenFOAM Hull Optimisation Study

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A study on the optimization of a RO-Ro hull form with the use of the Multiphase OpenFOAM solver interFoam.-- Revision 2 Edit - As the challenge was extended, out of interest I included a scenario with a number of hydrofoils designed to reduce the hull area in contact with the water. Results showed that the CFD was accurate at modelling the lift and drag but in conclusion the additional drag area brought by the wing even with the reduced hull area was a net decrease in efficiency.The following study made use of the CFD toolbox OpenFOAM, the solver was setup using the classic DTC Duisberg test case paper (Moctar El O, Shigunov V Zorn T, 2012). However the setup was modified for a full scale RO-RO Hull. The solver allowed for the interface between water and air to be modelled in detail giving accurate wave forces.The pressures on the hull panels were integrated across the hull length to give total drag force. The design focused upon reducing viscous and pressure drag forces by delaying boundary layer separation and cancelling the generation of hull side waves.The optimization of the hull bulb provided a good first step in wave cancellation and the design took parameters from current research.In order to provide a sensible optimization process the hull design was created by a modified Wigley equation. The optimized design gave a 12% reduction in total drag force and was described using the below equation (Each equation was subject to the limits that the enclosed volume below 0 , the water line, should equal 16000t of water):From L/2 - 0y = (b/2)*(1-(4*x^2/170^2)^2)*(1-((2*z/2)/6.5)^2)From 0- -L/2y = (b/2)*(1-(4*x^6/170^6)^2)*(1-((2*z/2)/6.5)^6)With a tangential surface to join in the mid section.