! " #$% % &% ’% ( 1 ) *$+ ,) ) % -.% ( ! / % -.% ( 0-1- A boundary element method (BEM) model is applied for the prediction of cavitating flow around 3D straight/swept hydrofoils between slip (zero shear) walls. The governing equation and boundary conditions are formulated and solved by assuming piecewise constant distribution of sources and dipoles on the hydrofoil and cavity surfaces, and piecewise constant distribution of dipoles on the trailing wake sheet. Cavity shape determination is initiated with a guessed cavity planform, and the cavity extent and thickness are determined iteratively until the dynamic and kinematic boundary conditions are satisfied on the cavity surface. To account for nonormal flow through the side walls, the method of images is used. For the fullywetted case, the attached flow results obtained are compared with results from a fullfledged ReynoldsAveraged NavierStokes (RANS) solver. The cavitating results for a straight wing between slip walls are compared with results from an existing 2D BEM solver for cavitating flow around hydrofoils. The RANS solver is also used to study separated flow characteristics around 2D/3D hydrofoils at high loading. 2’34-(13 C: Chord length of the 2D hydrofoil section : Pressure coefficient, = ( − )/( ) : Vapor pressure : Farfield pressure Re: Reynolds Number : Mean flow velocity in the i th coordinate direction : Fluctuating flow velocity in the i th coordinate direction : Friction velocity, = / : Nondimensional wall normal coordinate, = ( )/ α: Inflow angle of attack !: Sweep angle of the 3D wing/hydrofoil ν: Kinematic viscosity of the fluid ρ: Density of the fluid σ: Cavitation number, " = ( − )/( ) : Wall shear stress #: Perturbation potential -12+(-2 A number of techniques have been developed in recent years to treat wetted and cavitating flow around 2D/3D hydrofoils. Boundary Element Method (BEM) has been found to be a computationally efficient, robust and versatile tool for analysis of such flows. Kinnas and Fine (1991, 1993b); Fine and Kinnas (1993) have developed nonlinear potential based boundaryelement method for analysis of partially or supercavitating flows around 2D/3D hydrofoils. Their method was extended to predict face cavitation and search for cavity detachment on threedimensional hydrofoils and propellers by Kinnas (1998). In the present work, a BEM model has been developed to study wetted/cavitating flow around 3D straight/swept hydrofoils between slip walls. The BEM model is built over an existing robust numerical tool PROPCAV [PROPeller CAVitation, Kinnas and Fine (1992)]. PROPCAV is capable of analyzing 3D unsteady flow around cavitating propellers and is based on a loworder (piecewise constant dipole and source distribution) potential boundary element method. In the current work, to account for nonormal flow through side walls, an image model has been incorporated into PROPCAV. Figure 1 shows the top view of a swept hydrofoil spanning between walls that are parallel to the xy plane. For a straight wing between parallel walls, the sweep angle λ = 0 o (refer Fig. 3). The two side walls are treated as noshear or slip walls. Since the main emphasis is on predicting the influence of sweep on the hydrofoil pressure distribution, by treating the side walls as slip walls, comparisons between the inviscid 3D BEM model and a RANS solver (Fluent 1 ) are made in the absence of any tip effects that might have otherwise arisen. Furthermore, by choosing this simplistic, controlled environment, RANS calculations can be performed with a relatively lesser number of cells/elements. 1 Version 6.3.26, Website – http://www.fluent.com/