Vertical Drainage Simulator

Here is a simple applet to simulate the drainage of a thin film down a vertical substrate. The liquid is assumed Newtonian, of adjustable

• viscosity (poise),
• surface tension (dynes/cm),
• and specific weight (gm/sec²/cm²).

The initial profile is prescribed as a parabolic mound superimposed on a thin wetting layer. The thickness of the mound and of the wetting layer as well as the substrate length are all adjustable parameters.

The run parameters are

• the number of nodal points,
• the time step (in seconds),
• the maximum (physical) time (in seconds) after which the simulation is to be stopped,
• the rate of graphical output (in seconds).

After clicking the run button, the applet opens a graphical window which displays the evolution of the film at the specified instants. The simulation can be stopped, and a new run can be performed. The reset button erases the graphics and all input fields of the panel. By pressing the fill button, the axes can be adjusted to make the entire plot visible in the window. A rectangle can be drawn in the graphics panel to zoom in any portion of the plot.

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A more general applet with the following capabilities:

• 3D simulation of the flow of a liquid film over a flat substrate with variable inclination with respect to the vertical,
• Generalized Newtonian rheology (Ellis viscosity model, shear-thinning effect, etc),
• Arbitrary initial profile of film thickness,
• Adjustable liquid/solid contact angle,
• Variable time stepping (acceleration scheme),
• Contour graphics of surface elevation, cross-sectional profiles, etc.

can be found here .