[Date Index]
[Thread Index]
[Author Index]
Solving Ordinary differential equations by NDSolve
*To*: mathgroup at smc.vnet.net
*Subject*: [mg104962] Solving Ordinary differential equations by NDSolve
*From*: Allamarein <matteo.diplomacy at gmail.com>
*Date*: Sun, 15 Nov 2009 05:55:30 -0500 (EST)
I'd solve this ODE:
V'[t] == A Sqrt[2 (Po (V0/V[t])^gamma - Pa)/rho
IC: V[0] == V0
I wrote this code:
d = 2*10^-2 ;
A = d^2 3.14/4;
Po = 5 *101325;
Pa = 1*101325 ;
rho = 1000 ;
V0 = 5*10^-3 ;
gamma = 1.14;
sol = NDSolve[{
V'[t] == A Sqrt[2 (Po (V0/V[t])^gamma - Pa)/ rho],
V[0] == V0},
{V}, {t, 0, 9},
MaxSteps -> 1000000, AccuracyGoal -> 10, PrecisionGoal -> 10];
v[t_] := V[t] /. sol[[1]];
Plot[Evaluate[V[t] /. sol]*1000, {t, 0, 9}, PlotRange -> All]
Grid[Table[{t, v[t]}, {t, 0, 9, 1}]]
If it can be useful, I can underline units of these variables:
d [m]
P0, Pa [Pa]
rho [kg/m^3]
V [m^3]
gamma [--]
t [sec]
Running this code, V has got comlex part. This is impossible, because
it's a volume.
I should re-write my ODE in order NDSolve can digest better or I can
set an option in my code where I suggest " V must be positive and
real"?
Prev by Date:
**Re: Importing fonts into Inkscape**
Next by Date:
**Re: Displaying results in a column**
Previous by thread:
**Re: Preserve notebook's $ContextPath between sessions / store custom**
Next by thread:
**Re: Solving Ordinary differential equations by NDSolve**
| |