Berkeley Fluids Seminar
University of California, Berkeley
Bring your lunch and enjoy learning about fluids!
November 20, 2013
Prof. Orkan Umurhan (Applied Mathematics, UC Merced)
Goldreich-Schubert-Fricke Instability and Secondary Transition in Protoplanetary Disks
Recent theoretical work has demonstrated the relevance of the Goldreich-Schubert-Fricke instability as a dynamical mechanism for protoplanetary disks. In this talk I will cover recent work on this matter including the linear and nonlinear nature of the GSF and the conditions in an astrophysical disk in which it is expected to operate. Axisymmetric simulations show that the GSF grows into periodic structures of alternating vertical jets (with respect to the disk midplane) with some a corresponding modification of the basic Keplerian shear flow. Some new results to be presented include a characterization of the secondary transition of the periodic jet structures under axisymmetric perturbations which we find to be the mathematical analogue of the Holmboe instability and a model representation of this hypothesis is tested. These dynamics can be captured by a conceptually transparent Counterpropagating Kernal Gravity wave framework.