Special IGM Colloquium: Spots, stripes and bursts: Patterns in convectively driven shear flows.
Event details
| Date | 09.04.2020 |
| Hour | 16:00 › 17:00 |
| Speaker | Prof. Tobias Schneider |
| Location | |
| Category | Conferences - Seminars |
Abstract:
The transition to turbulence of fluid flows is ubiquitous, arising in our every-day experience when we ride a bicycle or take off in an airplane. Despite this ubiquity, the laminar-turbulent transition in wall-bounded flows is one of the least understood phenomena in fluid mechanics. During transition, the flow may self-organize into patterns with regular spatial and temporal structure, whose origins remain unexplained. A canonical flow exhibiting a large variety of complex spatio-temporal flow patterns is thermal convection in a fluid layer between two parallel plates kept at different temperature and inclined against gravity.
We study the dynamics of the so-called inclined layer convection (ILC) system, using a fully nonlinear dynamical systems approach based on a state space analysis of the governing equations. Exploiting the computational power of our highly parallelized numerical continuation tools (www.channelflow.ch), we construct a large set of invariant solutions of ILC and discuss their bifurcation structure. We show that unstable equilibria, travelling waves, periodic orbits and heteroclinic orbits form dynamical networks that support moderately complex dynamics at intermediate angles of inclination. At high inclination angles, localized patches of weakly turbulent convection within a background of straight longitudinal convection rolls are observed. We present exact invariant solutions capturing both the dynamics and the spatial localization of these so-called transverse bursts.
More generally, these results demonstrate how combining nonlinear dynamical systems methods with modern computational tools allows us to understand the complex behaviour that emerges in seemingly simple yet intrinsically nonlinear mechanical systems.
Bio:
Tobias Schneider is an assistant professor in the School of Engineering at EPFL, the Swiss Federal Institute of Technology Lausanne. He received his doctoral degree in theoretical physics in 2007 from the University of Marburg in Germany working on the transition to turbulence in pipe flow. He then joined Harvard University as a postdoctoral fellow. In 2012 Tobias Schneider returned to Europe to establish an independent Max-Planck research group at the Max-Planck Institute for Dynamics and Self-Organization in Goettingen. Since 2014, he is working at EPFL, where he teaches fluid mechanics and heads the 'Emergent Complexity in Physical Systems' laboratory.
Tobias Schneider's research is focused on nonlinear mechanics with specific emphasis on spatial turbulent-laminar patterns in fluid flows transitioning to turbulence. His lab combines dynamical systems and pattern-formation theory with large-scale computer simulations. Together with his team, Schneider develops computational tools and continuation methods for studying the bifurcation structure of nonlinear differential equations such as those describing the flow of a fluid. These tools are published as open-source software at channelflow.ch.
The transition to turbulence of fluid flows is ubiquitous, arising in our every-day experience when we ride a bicycle or take off in an airplane. Despite this ubiquity, the laminar-turbulent transition in wall-bounded flows is one of the least understood phenomena in fluid mechanics. During transition, the flow may self-organize into patterns with regular spatial and temporal structure, whose origins remain unexplained. A canonical flow exhibiting a large variety of complex spatio-temporal flow patterns is thermal convection in a fluid layer between two parallel plates kept at different temperature and inclined against gravity.
We study the dynamics of the so-called inclined layer convection (ILC) system, using a fully nonlinear dynamical systems approach based on a state space analysis of the governing equations. Exploiting the computational power of our highly parallelized numerical continuation tools (www.channelflow.ch), we construct a large set of invariant solutions of ILC and discuss their bifurcation structure. We show that unstable equilibria, travelling waves, periodic orbits and heteroclinic orbits form dynamical networks that support moderately complex dynamics at intermediate angles of inclination. At high inclination angles, localized patches of weakly turbulent convection within a background of straight longitudinal convection rolls are observed. We present exact invariant solutions capturing both the dynamics and the spatial localization of these so-called transverse bursts.
More generally, these results demonstrate how combining nonlinear dynamical systems methods with modern computational tools allows us to understand the complex behaviour that emerges in seemingly simple yet intrinsically nonlinear mechanical systems.
Bio:
Tobias Schneider is an assistant professor in the School of Engineering at EPFL, the Swiss Federal Institute of Technology Lausanne. He received his doctoral degree in theoretical physics in 2007 from the University of Marburg in Germany working on the transition to turbulence in pipe flow. He then joined Harvard University as a postdoctoral fellow. In 2012 Tobias Schneider returned to Europe to establish an independent Max-Planck research group at the Max-Planck Institute for Dynamics and Self-Organization in Goettingen. Since 2014, he is working at EPFL, where he teaches fluid mechanics and heads the 'Emergent Complexity in Physical Systems' laboratory.
Tobias Schneider's research is focused on nonlinear mechanics with specific emphasis on spatial turbulent-laminar patterns in fluid flows transitioning to turbulence. His lab combines dynamical systems and pattern-formation theory with large-scale computer simulations. Together with his team, Schneider develops computational tools and continuation methods for studying the bifurcation structure of nonlinear differential equations such as those describing the flow of a fluid. These tools are published as open-source software at channelflow.ch.
Practical information
- General public
- Free