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The usage of StopTime.
The usage of StopTime.
I want to calculate the change in potential energy as a water droplet is falling towards the ground and I also want to be able to change the start heignt of the drop in an easy way. To know where the droplet is I have defined the position of the droplet as
Code:
x=time;
. But to calculate the potential energy I have to know the distance to the ground as well.
What I want to do, is something like this:
Code:
Distance=(StopTime-x);
I have tried to use the code
Code:
annotation(experiment(StartTime = 0.0, StopTime = 6.0, Tolerance = 1e-006)…);
and then use StopTime as both a variable and or parameter without success.
I could just type in the start height of the falling drop and then choose the same stop time before simulate.
Is there an easier way to solve this?
/Joakim
Thank you
Re: The usage of StopTime.
Trust me, you never want to use "time" directly to model physical behaviour. Physics really is about relative time. You should probably do:
Code:
model M
parameter Real startPos = 100;
Real x(fixed=true,start=startPos);
Real distance = startPos-x;
equation
der(x) = -1.0;
when x < 0 then
terminate("drop hit the ground");
end when;
end M;
You get something like:
Code:
stdout | info | Simulation call terminate() at time 100.000000
| | | | Message : drop hit the ground
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