solving differential equations

Forum|Forum|14 years ago
March 13, 2012
3 replies
4547 views

Solving Torricelli's Law for the flow out of a cylindrical tank through a round hole is pretty straight forward. It can be done by direct integration. However, when trying to solve it numerically with rkfixed or odesolve I ran into some unexpected problems.

rkfixed gave the message: D(t,h) must be real ! odesolve would not not converge to the efflux time corresponding to h = o. With the substitution u = sq. root h, it was smooth sailing to use either program. Is this a tolerence issue? Something else? It it a pretty straight forward linear 1st degree differential equation after all!

WSU1963

Physics

H

HarveyHensley

12-Amethyst

I think your problem is that your equation may be trying to reach ln(0) which is not possible. When you changed to the sq root of h, it is trying to reach 0, which it can do. If I'm not correct, then supply the differential equation that you are trying to solve.