Thermally driven Keplerian turbulence

• Applicant: Xiaojue Zhu, Ph.D.
• Subject Area: Fluid Mechanics ; Astrophysics and Astronomy
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 550262949

The transfer of angular momentum in accretion disks from the center to the periphery is a crucial mechanism in the universe, driving the dynamic changes in these disks and with significant implications, such as planet formation and supermassive black hole growth. Although magnetic fields are recognized as significant players in this process, there is an ongoing search for a hydrodynamic mode of transport, as some disks are poorly ionized and weakly coupled to magnetic fields. In this context, the lack of magnetically-driven turbulence in such disks has stimulated interest in investigating purely hydrodynamic origins of turbulence. This proposal focuses on Taylor-Couette flow, a fluid confined between two co-rotating cylinders, in the quasi-Keplerian regime, a model widely adopted for the study of flow in accretion disks. Previous studies on pure quasi-Keplerian flow have not led to turbulence. In comparison, the aim here is to investigate the impact of radial stratification on the quasi-Keplerian flow, considering significant radial thermal effects in real situations. To tackle this problem, we will combine three methods, from linear stability analysis, to weakly nonlinear stability analysis, and to highly turbulent regimes at extreme parameters. The possible subcritical and supercritical transitions under different parameters will be studied, and direct numerical simulations will be conducted to reach the ultimate regime, the upper limit for angular momentum transport.

• DFG Programme: Research Grants
• International Connection: China, Singapore
• Cooperation Partners: Professor Chao Sun, Ph.D.; Professor Mengqi Zhang, Ph.D.