How to decode the file names
The files in the velocity archives contain the velocity profiles for various components (u,v,w) at times t=4, 8 or 12, with respect to different lines, in planes perpendicular to one of the coordinate axis and passing through the centroid of the cavity. For example the file named u4(y)_z.out contains the u-component of the velocity on the line parallel to the y-axis, passing through the centroid of the cavity (in the plane perpendicular to the z-axis). Each file has two columns, one of them containing the velocity component value, the other one -- the coordinate of the point with this velocity.
The files in the pressure archives contain the entire pressure disrtibution on planes perpendicular to the x, y or z-axis passing through the centroid of the cavity. The name of the file can be decoded as follows. Take as an example p4_x.dat. It contains the pressure at time t=4 in the plane orthogonal to the x-axis through the cetroid of the cavity. The data is stored in a vector of size NxM where N is the number of grid points in the first direction and M -- in the second direction. The "first" direction is relative to the direction perpendicular to the plane of the data. If the data is in a plane perpendicular to x then the first direction is y and the second is z. If it is perpendiclar to the y, then the first would be the z-direction and second -- the x direction etc. The pressure is stored line after line starting with the "bottom" line which is parallel to the first direction.
More details on the algorithm are available in: Guermond, Minev, START-UP FLOW IN A THREE-DIMENSIONAL LID-DRIVEN CAVITY BY MEANS OF A MASSIVELY PARALLEL DIRECTION SPLITTING ALGORITHM. In print in Int.J. Numer. Meth. Fluids.
For more info, e-mail me at firstname.lastname@example.org.