Dresden 2006 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 20: SYMPOSIUM Microfluidics I: Boundary conditions, manipulation, and transport

CPP 20.8: Vortrag

Donnerstag, 30. März 2006, 12:00–12:15, ZEU 160

Lattice Boltzmann studies of chaotic flows in microchannels — •Fathollah Varnik and Dierk Raabe — MPI fuer Eisenforschung, Max-Planck Strasse 1, 40237 Duesseldorf

Via lattice Boltzmann simulations, it is shown that a qualitative change in flow properties may be triggered by a variation of the wall roughness/geometry alone. In particular, a transition from a steady flow toward an unsteady chaotic flow is observed as the roughnes height in increased in shark teeth channels. Similar observations are also made for a random distribution of obstacles along the channel underlining the generality of the observed transition.

We focus on the impact of various roughness parameters on the transition showing that it is not the roughness height alone which determines the onset of flow instability. Rather, it is the combined effect of the roughness height- and wave length which is essential. In particular, by an increase of the roughness wave length, it is possible to trigger flow instability even if the roughness height is reduced.

In view of increasing number of potential applications of chaotic flows in civil engineering, environmental industry (e.g. solution recovery) as well as in the medical science (e.g. enhanced chaotic mixing in microchannels), the results of our studies may find a wide range of applications as they open an alternative way for tuning flow properties, namely via an appropriate channel design.