Skip to content

Instabilities and Bifurcations in Fluid Dynamics

Hydrodynamic instabilities in centrifugal, thermal and shear flows.

Towards a deterministic understanding of instabilities in fluids and transition to turbulence

Understanding why fluids in  motion may undergo transition to complex dynamics is of major relevance in many branches of science and technology, from atmospheric physics, aeronautics to even the medical study of blood motion within arteries.There are three main instability mechanisms that are responsible for this transition, namely: thermal buoyancy (responsible for triggering thermal convection in the atmosphere, for example), centrifugal effects (present in any rotating fluid system)  and shear (responsible for transition to turbulence in pipes and/or channels).

In nature, these three essential mechanisms act simultaneously. For instance, temperature gradients in atmospheric or oceanic dynamics may be affected by the Earth’s rotation, by shear produced in large-scale currents, or by time-periodic forcings of daytime, seasonal or astronomical nature such as tides. Therefore it is necessary to study the combined effects of more than two simultaneous mechanisms at play.

In the IBFD group, we address the prediction of such instabilities combining tools from very different nature, ranging from dynamical systems and bifurcation theory, to top-notch numerical and computational methodologies such as DNS (Direct Numerical Simulation), continuation of steady and time-periodic flows using Newton-Krylov-Poincare solvers and their linear stabilitiy analysis using Arnoldi methods.


In short, we will include here more details regarding each one of our research lines enlisted below:

 

Thermal instabilities

 

Centrifugal instabilities

 

Shear instabilities

 

 Temporarily, you can find detailed information of our research activities at:

http://www-fa.upc.es/websfa/fluids/marques/con_rot.html