I have solved the flow around a ship hull using CFX 4.3 and I have output the u, v and w velocities for each cell at constant x planes along the hull. I am interested in locating the centre of vortices from this data and was wondering what the most effective method would be.

Thanks in advance.

calculate vorticity, I would say =rot(U). Depends on the shape of the velocity field. If you have solid body rotation, then vorticity is zero.

Check out

D. Sujudi and R. Haimes, "Identification of Swirling Flow in 3D Vector Fields," AIAA-95-1715, 12th AIAA CFD Conference, 1995.

Adrin Gharakhani

Take a look at:

J. Jeong & F. Hussain 1995 On the identification of a vortex. J. Fluid Mech. 285, 69-94.

(1). If you are using a commercial code, then after you have obtained the solutions, you can move to the post-processing step. (2). What I always do, in addition to the display of contour plots and velocity vector plots, is to create an array of points for trajectory tracing (particle path). You can do this easily by selecting some initial points at mesh points or cells. You can also do the forward or backward tracing. (3). This is the easiest way to see the 3-D flow motion especially when there is a vortex (or vortices) in the flow field. (contour plot of vorticity can only display the result on a surface) So the tornado-like trajectories will give you the needed information in 3-D.