I cannot understand why t instead of V |
The goal of your ODESolve block is to get the function h(t) - at least thats how it is setup. But I was wrong about the t as the syntax for odesolve is a bit different compared to Mathcad (15 and below) which I use and am used to. odesolve(h(t),3600s) would be correct, without specifying the independent variable as this is already seen in h(t).
The origin of all your calculation is a set of discrete datapoints und you are about to do various calculations with it. You could have chosen to stay discrete throughout which I suppose could be possible. Of course you would not have integrals then but sums and no derivatives but ratios of differences. And so formulas out of reference books would have to be "retranslated".
You have chosen to work with continuous functions from the very beginning (your first question here was how to turn your data into a godd fitting function) and I can not decide if that decision was good or if it even was necessary.
But what I see now is that you are mixing continous (functions like h(t)) and discrete (Vectors like V) and this is calling for troubles.
it seems illogical that you would need Qout(h(t),t) when V itself is dh/dt or |
That wasn't what I tried to say. Assuming your function Q.out is setup correctly it requires a length as first and a velocity as second parameter. So t would not work as second argument. I had something like Q.out(h(t),V(t)) in mind. If V is really simply the derivative of h wrt t, why don't you write it that way? Or the other way round - if V is the derivative of h and you already know V (at as a vector of points), you could turn it into a function again and integrate.
You may make your ode solveblock solve for both h() and V() as I think Mathcad will not be happy if you feed dh(t)/dt into Q.out instead of V. That way solving a system of ODEs.
Your problem looks to me like some kind of two compartment model and I wonder why you do not end up with a DE of second order or a system of two ODEs of first order. But then I may be wrong, of course.
I should state again that I don't know about the things you are trying to calculate and am looking at it from a more abstract point of view. But I somehow get the impression you want to drill some holes in a wall and have already turned on a drill machine you are not acquainted with but still don't know where and at what diameter you want your holes exactly. Sorry for the comparison, but I have the impression that it would be a good idea to go back again to the drawing board sorting out the problem and to refine your mathematical model. I would guess that its not necessary to reinvent the wheel anyway and that working models are already available in the literature.
I attach a sheet where I have used your specification (V(t)=dh(t)/dt) and solved the system of ODEs, but the results obviously are not valid.
