engquist.h File Reference

Go to the source code of this file.

Functions
void	event_viscous_term (void)
	Event: viscous_term (i++)

Variables
double	efilter = 0.

Function Documentation

event_viscous_term()

void event_viscous_term

(

void

)

Event: viscous_term (i++)

The filter is only applied to extrema in the free-surface height \(\eta\) (first condition) contained within two inflection points (second condition): this effectively selects only grid-scale oscillations and avoid filtering smooth extrema.

We then compute the shift in the value of \(\eta\) necessary to smooth the extremum, see Algorithm 2.1 in Engquist et al, 1989.

We apply only part of the correction, weighted by the timescale.

Definition at line 24 of file engquist.h.

References _i, a, d, dimension, dp, dry, dt, efilter, eta, foreach_layer, h, min, s, x, and zb.

Variable Documentation

efilter

double efilter = 0.

Filter for grid-scale oscillations

Note that this is obsolete and is kept only for historical interest.**

Because it is colocated, the layered solver can be prone to grid-scale oscillations. This noise is usually small but can be significant when gradients of bathymetry/wave fields are under-resolved.

The filter below can be used to reduce this noise. It is inspired from the work of Engquist et al, 1989.

The strength of the filter is controlled by the filtering timescale filter: the smaller the value, the stronger the filter. This can be interpreted as the timescale during which a disturbance must not move to be seen by the filter.

Definition at line 21 of file engquist.h.

Referenced by event_viscous_term().