Prediction of Turbulent Ship Air-Wake Characteristics

Abstract

This paper presents an external flow application of PHOENICS. The problem is concerned with the prediction of air-wake environment near the landing deck of a ship. Flow is turbulent, three-dimensional and elliptic. The major feature of problem formulation is the selection of “body fitted coordinates (RFC)” or “porosity” approach. Due to the presence of multiple, discontinuous structures and objects on ships, the porosity approach has been selected. For the first stage of study, modest size computational cells and standard k ∼ ε model of turbulence have been used. Computations for different wind speed and direction have been made for a one-eightieth scale model ship for which wind-tunnel experimental data are available.

Calculated distributions of velocity and turbulence kinetic energy compare well at all positions except one which is closest to the hangar. To analyze possible contributing factors, additional calculations are made with the inclusion of: (a) the support rack of probes, and (b) the probe itself. This analysis shows that the flow disturbances due to intrusive measurements are significant and in the right direction to explain the differences observed between the calculated and measured velocites. Overall, this paper shows that PHOENICS predicts correct characteristics of the air-wake.