Hi,
In a model that I am working on, I am estimating the flow across a series of small line segments. However, changing the darcy flux calculation to elemental rather than nodal gives very different values in places. Can anyone explain why this might be?
My model has a series of different K values e.g from west to east, with the node locations indicated by the yellow asterisks:
[color=grey][b]NORTH[/b][/color]
[color=grey][b]WEST [/b] [/color] |------------------------------[color=red]K1[/color]---------------------------|--------[color=green]K2[/color]-------|--------[color=blue]K3[/color]------| [color=grey][b]EAST[/b][/color]
[color=yellow] * * * * * * * * * * * * [/color]
|
|
| (flow direction)
V
[color=grey][b]SOUTH[/b][/color]
...the model extends above and below the diagram (with nodes in the same pattern) and all flow going from north to south.
[b]With the nodal setting I get the following amounts:[/b]
Q in [color=red]K1[/color] = 52 m3/d
Q in [color=green]K2[/color] = 34 m3/d
Q in [color=blue]K3[/color] = 210 m3/d
[b]With the elemental setting I get the following amounts:[/b]
Q in [color=red]K1[/color] = 50 m3/d
Q in [color=green]K2[/color] = 8 m3/d
Q in [color=blue]K3[/color] = 240 m3/d
For some reason the flow in the [color=green]K2[/color] region seems to change significantly, where as the other two seem fairly similar, what might be the reason for this? Is the low number of nodes a problem? It's a fairly unrefined part of the model..
Thanks,
SB