Please could someone tell me how to calculate the vorticity magnitude.

Thanks

Compute the curl of velocity and take the magnitude of the vector.

wx = dw/dy - dv/dz wy = du/dz - dw/dx wz = dv/dx - du/dy

w = wx(i) + wy(j) + wz(k)

vorticity magnitude = sqrt(w.w) = sqrt( wx*wx +wy*wy +wz*wz)

Could this function be defined into any cfd post.

[la7low]

|w|=||wij||

where wij is the vorticity tensor defined as the antysymmetric part of the velocity gradient tensor. Its magnitude defined by:
||wij||=sqrt(2wij*wij)
and its the same as the magnitude of the vorticity vector as defined earlier.