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Mayank Sahni
03/25/01 9:54pm


i'm new to mathematica and i'm having considerable difficulty solving the following problem.can someone please help me out and tell me what i'm doing wrong
here.I want to plot S v/s B and also q_s v/s B for various values of B.
n,F,S all involve q_s and B therefore the p.d's have to be solved simultaneously

Da = 0.1
Le = 1
g = 20
ord = 1
q = 0
x = 0
sol1 = DSolve[{
n = (3*phi*Coth[3*phi] - 1)/(3*phi^2),

phi = Sqrt[Exp[q_s/(1 + q_s/g)]],

D[F[q_s, phi, B], q_s] + (q_s - q)*(1/n)*D[n[q_s, phi, B], q_s] =
1 - (q_s -
q)*{1/((1 + q_s/g)^2) - {(ord*Le/B)/(1 -
x - (Le/B)*(q_s - q))}},

D[F[q_s, phi, B],
B] = -(q_s - q)*(1/
B + (1/n)*(D[n[q_s, phi, B],
B]) - {(ord*Le*(q_s - q)/B^2)/(1 -
x - (Le/B)*(q_s - q))}),

D[n[q_s, phi, B],
phi] = {(9*phi^2 + 2 - 3*phi*Coth[3*phi][1 + 3*p*Coth[3*phi]])/(3*
phi^3)},

D[n[q_s, phi, B], q_s] =
D[n[q_s, phi, B],
phi]*(phi/
2)*{1/((1 + q_s/g)^2) - {((ord - 1)*Le/B)/(1 -
x - (Le/B)*(q_s - q))}},

D[n[q_s, phi, B], B] = 0,

F[q_s] = (q_s - q) - (B*Da/Le)*
Exp[q_s/(1 + q_s/g)]*(1 - x - (Le/B)*(q_s - q))*n = 0,

S = -{(B/q_s)*(D[F[q_s, phi, B], B]/D[F[q_s, phi, B], q_s])},}]
Plot[Evaluate[{S} /. sol1, {q_s} /. sol1], {B}]


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Subject (listing for 'Partial differential equations')
Author Date Posted
Partial differential equations Mayank Sahni 03/25/01 9:54pm
Re: Partial differential equations Henry Lamb 03/28/01 3:00pm
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