Werner;
I cannot understand why t instead of V. I agree V is a vector because its value changes with the depth of water hw which is the parameter feed to the Qout function above the solve block. Qout isin fact a function of hw and V because hw i.e the total depth i.e. head of water above the base of the tank which drives the velocity in the outlet pipe. I agree that h is a function of t as in h(t) because that is the function of the ODE one is trying to find i.e. the depth of water in the tank from one time step to the next. How then h(t),t what is the second t for I agree I left the units out of the inital condition as you say I should have h(0s)=0m as you point out but why t instead of V because as you can see the plot above the solve plot is plotting the function correctly and it uses hw and V but not t? Maybe I missing some subtle point, my math certainly needs a good refresher but that said it seems illogical that you would need Qout(h(t),t) when V itself is dh/dt or as I see it the rate at which water is draining or filling the tank at least that is intuitivly correct i.e. maps to the reality of the situation in my view. Please show me what you mean because I made the changes you suggested and it still dosn't work. As you said previously it not just making the solve block happy it must be solving real world things.
Kind regards, Mark