Thanks Pete.

You are right, I figured out that Feflow interpolates the values at
t=0 and t=730. As you said the only way to switch off the 1st boundary
condition is to use the constrains. I my case it was easy cause I was
simulating a time variant seepage condition (some horizontal holes
built in different periods) and from 0 to 729 I assumed a fake
head=999 with the constrain in the maximum flow (=0).

Thank you very much. I had a confimation I have done the right thing though !

Gio


On Sun, Feb 15, 2009 at 3:18 AM, Pete Sinton <psinton@...> wrote:
> Hi Gio,
>
> I searched my notes and manuals about this and came up with nothing. In
> all the examples I've seen, the first time is always zero, and I have
> been in habit of setting up my power functions this way for a long
> time. I don't remember what FEFLOW assumes for a situation like you
> describe, but my guess is that it will either use the value at time 730
> for the value at time 0 or will set the value to 0 at time 0 and
> interpolate between time 0 and time 730.
>
> There is no direct way of "turning off" (deactivating) a boundary
> condition (BC) within a single feflow model, unless you use the
> SwitchBC module which you'd have to get from WASY. In some cases a BC
> node can be deactivated using BC constraints, but this will not always
> work (especially as the model complexity or number of such constraints
> increases). You can also deactivate a BC by using two feflow models,
> one that simulates a portion of time without the BC, and one set up with
> it. The first model would be used to initialize the second. Run a
> model from zero to 730 without the BC, use the result to initialize a
> second model that has the time varying BC.
>
> Pete