tension.h File Reference

#include "iforce.h"
#include "curvature.h"

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Functions
void	event_stability (void)
	Event: stability (i++)
void	event_acceleration (void)
	Event: acceleration (i++)

Variables
	attribute
	The surface tension coefficient is associated to each VOF tracer.

Function Documentation

event_acceleration()

void event_acceleration

(

void

)

Event: acceleration (i++)

Definition of the potential

We overload the acceleration event to define the potential \(\phi=\sigma\kappa\).

We check for all VOF interfaces for which \(\sigma\) is non-zero.

If \(\phi\) is already allocated, we add \(\sigma\kappa\), otherwise we allocate a new field and set it to \(\sigma\kappa\).

Definition at line 76 of file tension.h.

References curvature(), f, scalar::i, phi, and x.

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event_stability()

void event_stability

(

void

)

Event: stability (i++)

We need to overload the stability event so that the CFL is taken into account (because we set stokes to true).

Stability condition

The surface tension scheme is time-explicit so the maximum timestep is the oscillation period of the smallest capillary wave.

\[ T = \sqrt{\frac{\rho_{m}\Delta_{min}^3}{\pi\sigma}} \]

with \(\rho_m=(\rho_1+\rho_2)/2.\) and \(\rho_1\), \(\rho_2\) the densities on either side of the interface.

We first compute the minimum and maximum values of \(\alpha/f_m = 1/\rho\), as well as \(\Delta_{min}\).

The maximum timestep is set using the sum of surface tension coefficients.

Definition at line 39 of file tension.h.

References _i, alpha, c, cube(), dmin, dt, dtmax, fm, HUGE, max, min, pi, sigma, vector::x, and x.

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Variable Documentation

attribute

attribute

Initial value:

{
  double sigma

The surface tension coefficient is associated to each VOF tracer.

Surface tension

Surface tension can be expressed as the interfacial force density

\[ \phi\nabla f \]

with \(f\) the volume fraction describing the interface and the potential

\[ \phi = \sigma\kappa \]

with \(\sigma\) the (constant) surface tension coefficient and \(\kappa\) the interface mean curvature.

Definition at line 23 of file tension.h.