Is it possible to declare (or re-declare) components depending on the value of a time-dependent variable (as opposed to a parameter)? Conditional declaration has been discussed here numerous times (e.g., #1, #2 and #3), however in those examples, the condition depends on a parameter.
My situation is this: I have two models, NaturalConvectionHeatTransfer and ForcedConvectionHeatTransfer that extend from the same interface PartialHeatTransfer. In a third model, I would like to do something like this:
model MyProblem
// stripped other declarations
input v "Velocity of fluid flow";
replaceable PartialHeatTransfer heatTransfer;
equation
if v == 0 then
// redeclare heatTransfer to be of type NaturalConvectionHeatTransfer
else
// redeclare heatTransfer to be of type ForcedConvectionHeatTransfer
end if;
end MyProblem;
A conditional declaration like Component blah if v==0; certainly does not work if v is not a parameter. Is there any way to achieve my goal? My guess is "no", meaning I will have to re-think the whole concept. However, perhaps someone sees an obvious solution I am missing. Any suggestion how to work around this would be appreciated.
It is not possible. You can, however, model around it by adding both heatTransfer components and switch between them using some dummy components and equations.
http://dx.doi.org/10.3384/ecp14096183 has some implementation hints on how to do it in Modelica slightly inefficiently (and how tools could optimize some of those things away).