Jerry Sellwood is the world's leading N-body explorer
of the complex dynamical evolution of disk galaxies, driven
by their global instabilities, bars, stochastic spiral
patterns, warps, and the like. For more than three decades,
his numerical experiments have stood out because of their
elegance, high accuracy and the abundant care that he has
taken to compare his results with both theoretical analyses
His accomplishments have included the first simulations of galaxy disks with live halos, the first dissections of N-body bars to reveal their orbit families, the first demonstration of a buckling instability that thickens bars vertically, and several lines of work indicating that the dark halos contribute relatively little to the mass interior to the visible stellar disks of galaxies, even though their effects on the rotation curves and warps of the outlying gas disks remain profound.
Sellwood has also made influential contributions to the difficult problem of spiral structure in isolated disk galaxies. His two papers with Carlberg in 1984/85 and another with Kahn in 1991 did a lot to help shift the focus of that field from initial hopes for quasi-steady global modes to locally generated spiral features, with many implications for radial mixing, gas infall, and recurrent instabilities.
All this work has resulted in more than 60 papers in the refereed literature, and almost as many from various conferences. Sellwood has also published three major review articles, and has edited the proceedings of three significant conferences which he had largely organized. His influence has been further spread by his well-trained Ph.D. students.