Terminology¶
The purpose of this page is to introduce some D-Claw-specific terminology used throughout the digger documentation. This is meant to support users who are not familiar with D-Claw in understanding what digger does and why. It is not a replacement for understanding the theory and practice of using D-Claw.
D-Claw solves a set of depth-averaged differential equations for the motion of a granular fluid through time over a fixed basal surface, \(b\) (George and Iverson, 2014; Iverson and George, 2014). As material of thickness \(h\) moves over the basal surface, the surface elevation \(\eta\) changes. The digger documentation refers to a number of different variables that correspond to information needed by D-Claw. The D-Claw solution (i.e., the solution to the differential equations through time) is referred to as q, and the set of auxiliary variables that are used as part of finding the solution is called aux. Accordingly, some of the terminology that digger uses will refer to elements of q and aux. The names of these variables, their units, their relationship to q and aux, and a description are provided here:
Variable Name |
Element of q or aux |
Units |
Description |
|---|---|---|---|
\(b(x,y)\) |
- |
m |
Spatially variable elevation of a basal surface over which material may move. This is typically topography or merged topography and bathymetry. |
\(h(x,y,t)\) |
q1 |
m |
Spatially and temporally variable thickness of material which may move. |
\(\eta(x,y,t)\) |
q8 |
m |
Spatially and temporally variable value for the surface altitude \((b+h)\). Where \(h=0\), \(\eta=b\) and \(\eta\) represents the basal topobathymetric surface elevation. Where \(h>0\), \(\eta\) represents the altitude of the flow surface. |
\(m(x,y,t)\) |
q4 |
- |
Spatially and temporally variable value of solid volume fraction. |
\(h_e(x,y)\) |
aux5 |
m |
Spatially variable initial thickness of erodible material. |
This list is not a comprehensive list of the elements of q and aux, rather it is a list of the most relevant elements for digger.
As digger.make creates input files, the files it generates represent \(h\), \(\eta\), and \(m\) at simulation time = 0.
References
George, D.L., and Iverson, R.M., 2014, A depth-averaged debris-flow model that includes the effects of evolving dilatancy—II. Numerical predictions and experimental tests: Proceedings of the Royal Society of London. Series A, v. 470, no. 2170, p. 20130820, https://doi.org/10.1098/rspa.2013.0820.
Iverson, R.M., and George, D.L., 2014, A depth-averaged debris-flow model that includes the effects of evolving dilatancy—I. Physical basis: Proceedings of the Royal Society of London. Series A, v. 470, no. 2170, p. 20130819, https://doi.org/10.1098/rspa.2013.0819.