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Suppression of eddies in films over topography
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10.1063/1.3504374
/content/aip/journal/pof2/22/11/10.1063/1.3504374
http://aip.metastore.ingenta.com/content/aip/journal/pof2/22/11/10.1063/1.3504374
View: Figures

Figures

Image of FIG. 1.
FIG. 1.

Viscous film flow down a wavy incline.

Image of FIG. 2.
FIG. 2.

Experimental setup. The eddy size is determined by detecting the path lines of the tracers with the horizontal camera (1). The inclined camera (2) images the light sheet from the airside. The surface contour corresponds to the upper borderline of the bright sheet as seen by this camera.

Image of FIG. 3.
FIG. 3.

Comparison of experimental path lines to numerical streamlines. The image is rotated by the inclination of the channel. The volume flux is continuously increased from (a) to (d). (a) : no eddy at low Reynolds numbers. (b) : increasing inertia results in the generation of an eddy in the trough of the undulation. (c) : increasing inertia further, the eddy vanishes. (d) : flow separation reappears at even higher Reynolds numbers. Bottom contour: lower bright sinusoidal line; lines below and inversely bent lines in the upper part of the pictures are reflections of the path lines at the bottom and at the free surface. Channel inclination angle: 8°.

Image of FIG. 4.
FIG. 4.

Comparison of experimental and numerical free-surface shapes at different Reynolds numbers. Experimental data are represented by symbols; numerical data are represented by lines. The free-surface positions of each data set are shifted perpendicular to the mean-flow direction to avoid overlapping. The vertical position augments with the Reynolds number. Channel inclination angle: 8°.

Image of FIG. 5.
FIG. 5.

Cross-sectional area of the eddy as a function of the Reynolds number at different inclination angles. Experimental and numerical data are represented by open and solid symbols, respectively. At least 40 measurements per inclination angle have been carried out from to in equidistant steps. Where no eddy was observed, most data points have been blanked out for clarity.

Image of FIG. 6.
FIG. 6.

Amplitude of the first harmonic of the free surface as a function of the Reynolds number at different inclination angles. Experimental and numerical data are represented by symbols and lines, respectively.

Image of FIG. 7.
FIG. 7.

Amplitude of the second harmonic of the free surface as a function of the Reynolds number at different inclination angles. Experimental and numerical data are represented by symbols and lines, respectively.

Image of FIG. 8.
FIG. 8.

Mean film thickness averaged over one bottom period as a function of the Reynolds number at different inclination angles. Experimental and numerical data are represented by symbols and lines, respectively.

Image of FIG. 9.
FIG. 9.

Amplitude of the first two Fourier components and the mean film thickness for a channel inclination of 8°. The transition Reynolds number is indicated by a dashed line. Experimental and numerical data are represented by symbols and by lines, respectively.

Image of FIG. 10.
FIG. 10.

Spatial dependence of the local Froude number at different Reynolds numbers. Crests of the topography are at 0 and . The Reynolds number increases continuously from the lowest to the uppermost line. Below transition, the Froude number changes from subcritical to supercritical; beyond transition, it remains supercritical. Channel inclination angle: 8°.

Image of FIG. 11.
FIG. 11.

Comparison of the position of the surface shape transition and the eddy-free window position at different channel inclinations. Experimental data are represented by open symbols; numerical data are represented by solid symbols.

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/content/aip/journal/pof2/22/11/10.1063/1.3504374
2010-11-18
2014-04-24
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Suppression of eddies in films over topography
http://aip.metastore.ingenta.com/content/aip/journal/pof2/22/11/10.1063/1.3504374
10.1063/1.3504374
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