عباس دشتی منش

Current paper presents a virtual mathematical model for PMM test of planing hulls. This model, developed based on the recent progresses in modeling of planing hulls, uses empirical and semi-analytical solutions of water entry. The model considers various degrees of freedom for wedge entering water with oblique speed and angular motion. Pure yaw and sway tests are mathematically modeled, providing us with all the forces and moments acting on the boat. In addition, based on proposal of previous researchers, heave, pitch and roll motions of the boat are set to be free, computed during simulations. Accuracy of the method is examined by comparing its results against previous experimental measurements, indicating a reasonable accuracy. Samples of predicted results contain vessel motion, amplitude of motions, observed frequencies and hydrodynamic coefficients are computed. It has been observed that increase in amplitude of sway or yaw motion highly increases the amplitude of other dependent motions. Beside this, it has been inferred that increase in speed causes decrease in amplitude of motion. Later, hydrodynamic coefficients of boat have been determined, showing that they are independent of frequency. At the final stage of simulations, it has been seen that when boat is fixed in roll, heave and pitch motions, its hydrodynamic coefficients reduces.