Using "If" in ModelMuse to only apply package to cells matching certain criteria?

[Chris Russoniello]

I want to apply a head of zero to all ocean cells with the CHD package in a Modflow model I'm building in ModelMuse. Cells that are above sea level should not have a constant head applied. I was hoping to draw a big box around the entire domain and use an if statement so that the CHD boundary is only set in cells with a model top elevation < = 0. I thought something like "If(Model_Top <= 0, 0, $N/A)" might work, but I'm not sure if ModelMuse has a "do not compute" token. Is there a simple way to do this, or am I better off creating an ocean shapefile in GIS and using that shape to assign ocean heads?

Thank you,

Chris

[ashutosh singh]

Please read the definition of the term boundary when a PDE is used for a finite domain and how it influences the computed state variable in the domain.

Boundary will be imposed on the domain irrespective of the fact that the cells lie above sea level or below sea level. 

The cells above sea level will dry out because the computed head is below the bottom of the cell which lies above sea level.

Do not compute token is used as INACTIVE region in Modflow. Also assigning a constant head boundary means that the head will remain the same and is kind of non computed during the simulation.

For suggestion, try to look what you want to compute and start an iterative procedure of developing the model starting with the simplest model.

hpc

--
You received this message because you are subscribed to the Google Groups "MODFLOW Users Group" group.
To unsubscribe from this group and stop receiving emails from it, send an email to modflow+u...@googlegroups.com.
To post to this group, send email to mod...@googlegroups.com.
Visit this group at http://groups.google.com/group/modflow.
For more options, visit https://groups.google.com/d/optout.

[Chris Russoniello]

hpc,

Thank you for the quick reply. I think you I'm trying to do what you suggest -- impose a CHD boundary on only ocean cells, but not impose that boundary on land cells where I'd like the model to calculate heads. I imagine there's some way to have the GUI only write certain cells into the .chd input file by using an if/then statement, rather than needing to generate a new shapefile in a GIS program. My assumptions have been incorrect before.

In my earlier example, I was hoping the "do not compute" token would instruct ModelMuse to not to add a cell to the input file, rather than instruct Modflow to make the cell inactive. 

To clarify my original question: is there a way from within the ModelMuse GUI to impose a boundary (e.g. CHD) on only certain cells that meet a certain criterion. If not, is my best/only option to create a polygon defining the region where I'd like that boundary applied?

Cheers,

Chris

[Richard B. Winston]

The best way to do this is to use the formula for the Z Coordinate to
put the object above the top of the model except where you want it to
apply. For example, you could set the Z formula to "If(Model_Top > 0,
Model_Top + 1, Model_Top). Then for the formula for CHD, you could just
use 0.

> --
> You received this message because you are subscribed to the Google
> Groups "MODFLOW Users Group" group.
> To unsubscribe from this group and stop receiving emails from it, send
> an email to modflow+u...@googlegroups.com

> <mailto:modflow+u...@googlegroups.com>.

> To post to this group, send email to mod...@googlegroups.com

> <mailto:mod...@googlegroups.com>.

[Chris Russoniello]

Dr. Winston,

Thank you very much. That worked perfectly.