Dresden 2006 – wissenschaftliches Programm

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DY: Dynamik und Statistische Physik

DY 46: Poster

DY 46.8: Poster

Donnerstag, 30. März 2006, 16:00–18:00, P1

Influence of external flows on dendritic growth: numerical investigation — •Dmitry Medvedev and Klaus Kassner — Otto-von-Guericke University Magdeburg, Universitaetsplatz 2, 39106 Madgeburg, Germany

We use a combined phase-field/lattice-Boltzmann scheme [1] to simulate dendritic growth from a supercooled melt in external flows. Several regions of the morphology diagram (in the supercooling – anisotropy – flow velocity coordinates) were explored.

At moderate to high undercooling and high anisotropy, data fall approximately onto unique curve in the Peclet number – tip radius plane. Hence, it could be argued that a parallel flow changes the selected tip radius and growth velocity solely by modifying (increasing) the Peclet number.

For smaller anisotropy, an interesting phenomenon is observed. The growth velocity for dendrites increases faster than for doublons with increase of the flow velocity (at the same undercooling and anisotropy). For some parameters, dendrites become faster, hence, external flow can appreciably change the morphology diagram.

For small anisotropy and Prandtl number, oscillations of the tip velocity are observed. Increase of the fluid viscosity damps these oscillations.

[1] D. Medvedev, K. Kassner, Phys. Rev. E 72, 056703 (2005)