flood calculation

Forum|Forum|13 years ago
July 31, 2012
1 reply
2442 views

Hi,

I am trying to solve differential equations with ODE solver. In defining the solver, there is always a message " the number of rows returned from the function arguments does not match the number of equations to be solved.

Anyone can help?

Thanks

Krisnandito

1_MCR-flood-mcdx.zip

Calculus_Derivatives

Best answer by AlanStevens

AlanStevens wrote:
... I suspect one of your square root terms becomes imaginary (probably the H4-Hmcr term which is close to zero at 620 seconds) and odesolve doesn't like this.

Yes, if you prevent H4-Hmcr from going negative it works ok - see attached. In the attached I set H4-Hmcr to zero if it tries to go negative. This might or might not be the right thing to do physically for your flood scenario.

Alan

A

AlanStevens

19-Tanzanite

Set tend to no more than 620 seconds and it works fine. After that I suspect one of your square root terms becomes imaginary (probably the H4-Hmcr term which is close to zero at 620 seconds) and odesolve doesn't like this. The error message is not helpful!

Alan

A

AlanStevens

Answer

19-Tanzanite

AlanStevens wrote:
... I suspect one of your square root terms becomes imaginary (probably the H4-Hmcr term which is close to zero at 620 seconds) and odesolve doesn't like this.

Yes, if you prevent H4-Hmcr from going negative it works ok - see attached. In the attached I set H4-Hmcr to zero if it tries to go negative. This might or might not be the right thing to do physically for your flood scenario.

Alan

1_MCR-floodb-mcdx.zip