TY - JOUR

T1 - Characterization of the thermal and solutal Marangoni flows of opposite directions developing in a cylindrical liquid bridge under zero gravity

AU - Jin, Chihao

AU - Sekimoto, Atsushi

AU - Okano, Yasunori

AU - Minakuchi, Hisashi

AU - Dost, Sadik

N1 - Funding Information:
This work was partially supported by JSPS KAKENHI, Grant No. JP19K22015. The computations were carried out using the computational resources of Research Institute for Information Technology, Kyushu University, Japan.
Publisher Copyright:
© 2020 Author(s).

PY - 2020/3/1

Y1 - 2020/3/1

N2 - Numerical simulations of the thermo-solutal Marangoni convection developing in a Si-Ge liquid bridge of a floating-zone system have been performed under zero gravity. Half of the liquid bridge was considered as the three-dimensional (3D) computational domain. In this system, the solutal Marangoni convection develops in the direction opposite to the thermal Marangoni convection along the free surface in the bridge, i.e., the thermal Marangoni number, MaT, is negative and the solutal Marangoni number, MaC, is positive. Since the SiGe melt is a low-Prandtl number (Pr = 6.37 × 10-3) and high-Schmidt number (Sc = 14.0) liquid, the temperature field is almost independent of the convective flow and the concentration field determines the transport structures. When MaC is larger than -MaT, the concentration pattern is steady and two-dimensional (2D) axisymmetric. When MaC is smaller than -MaT, we predict two kinds of flow transitions with the increase in |MaT|. If MaC is sufficiently large (MaC ≳ 530), as |MaT| increases, the flow changes from a 2D-steady pattern to a 3D-chaotic behavior at moderate |MaT| (1050 ≲ |MaT| ≲ 2800). We also predict that a second transition and an oscillatory rotating flow occur as |MaT| increases further. The flow becomes 3D-steady at smaller MaC (MaC ≲ 360) with no transition, and the azimuthal wavenumber (m) decreases with increasing |MaT|. Furthermore, the thermo-solutal Marangoni convection in this system can be suppressed almost completely when MaC is approximately equal to -MaT (MaC ≈ -MaT) and the flow becomes periodically stable with weak fluctuations.

AB - Numerical simulations of the thermo-solutal Marangoni convection developing in a Si-Ge liquid bridge of a floating-zone system have been performed under zero gravity. Half of the liquid bridge was considered as the three-dimensional (3D) computational domain. In this system, the solutal Marangoni convection develops in the direction opposite to the thermal Marangoni convection along the free surface in the bridge, i.e., the thermal Marangoni number, MaT, is negative and the solutal Marangoni number, MaC, is positive. Since the SiGe melt is a low-Prandtl number (Pr = 6.37 × 10-3) and high-Schmidt number (Sc = 14.0) liquid, the temperature field is almost independent of the convective flow and the concentration field determines the transport structures. When MaC is larger than -MaT, the concentration pattern is steady and two-dimensional (2D) axisymmetric. When MaC is smaller than -MaT, we predict two kinds of flow transitions with the increase in |MaT|. If MaC is sufficiently large (MaC ≳ 530), as |MaT| increases, the flow changes from a 2D-steady pattern to a 3D-chaotic behavior at moderate |MaT| (1050 ≲ |MaT| ≲ 2800). We also predict that a second transition and an oscillatory rotating flow occur as |MaT| increases further. The flow becomes 3D-steady at smaller MaC (MaC ≲ 360) with no transition, and the azimuthal wavenumber (m) decreases with increasing |MaT|. Furthermore, the thermo-solutal Marangoni convection in this system can be suppressed almost completely when MaC is approximately equal to -MaT (MaC ≈ -MaT) and the flow becomes periodically stable with weak fluctuations.

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U2 - 10.1063/1.5142071

DO - 10.1063/1.5142071

M3 - Article

AN - SCOPUS:85082045043

SN - 1070-6631

VL - 32

JO - Physics of Fluids

JF - Physics of Fluids

IS - 3

M1 - 034104

ER -