In the present study, an unsteady three-dimensional flow simulation based on the RANS (Reynolds Average Navier-Stokes) equations with k-ε turbulence model and Singhal et al.’s cavitation model is conducted to study the cavity development behavior of two slender bodies, that is, a flat-headed cylinder and a step-headed cylinder of 50 mm in length and 10 mm in diameter. Using so called VOF method to track the liquid-vapor phase interface, time dependent solutions with varying approach speed range from 10 m/s to 55 m/s are obtained and analyzed to provide key information such as cavity initiation speed, drag coefficient and the cavity shape and size (max. length and diameter). The implemented numerical model is validated for flows over a flat disk cavitator against the experimental correlation. According to the present simulation results, slender bodies with two different head shapes, that is, a flat cylinder and a stepped one, respectively, showed very close behavior in their cavity initiation speed, maximum developed cavity diameter and length, but consistently lower drag coefficient with the step-headed cylinder case, which suggests the possible advantage of seeking optimized cavitator shape.

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