Ed:
In your message to the SD List Server (SD0306), you attributed a stock flow
model to me though it was not my handy work.
But I did want to respond to your post with the attached, very simple ithink
model ("Ed_Drain.itm"). In your discussion of draining water/drug
absorption
adioactive decay, you describe what we at High Performance
Systems generically call a "Draining Process." In this structure, a stock
generates its own outflow. If you wish, you can accumulate in a downstream
stock whats flowing, but this is not required to specify the flow as a
draining process. By adjusting the drain fraction, you can accelerate or
slow down the rate of flow. But whatever the fraction, the *relationship*
remains constant: stock * fraction of the stock per time = flow per time.
In isolation, e.g. no inflow to the Water in Barrel 1 stock, this structure
will generate exponential decay of the Water in Barrel 1 stock.
Hope this helps.
Paul Kucera
High Performance Systems
PKucera@aol.com
[Hosts Note: The attached file was removed since it would not properly transmit
through the remailer. If you can read MIME files you should send Paul a note to
retransmit it directly.]