Warped H I gas layers in the outer regions of spiral galaxies usually display a
noticeably twisted structure. This structure almost certainly arises primarily
as a result of differential precession in the H I disk as it settles toward a
preferred orientation in an underlying dark halo potential well that is not
spherically symmetric. In an attempt to better understand the structure and
evolution of these twisted, warped disk structures, we have adopted the
"twist equation" formalism originally developed by Petterson to study
accretion onto compact objects. Utilizing more recent treatments of this
formalism, we have generalized the twist equation to allow for the treatment of
non-Keplerian disks and from it have derived a steady state structure of twisted
disks that develops from free precession in a nonspherical, logarithmic halo
potential. We have used this steady state solution to produce H I maps of five
galaxies (M83, NGC 300, NGC 2841, NGC 5033, NGC 5055), which match the general
features of the observed maps of these galaxies quite well. In addition, the
model provides an avenue through which the kinematical viscosity of the H I disk
and the quadrupole distortion of the dark halo in each galaxy can be quantified.
This generalized equation can also be used to examine the time-evolutionary
behavior of warped galaxy disks.