How to solve a system of PDAEs with eigenvalue

In summary, the conversation discussed a system of partial differential algebraic equations with given conditions and the question of how to solve it numerically.
  • #1
ktsharp
8
0
I have the following system of partial differential algebraic equations:

[ tex ] \frac{1}{H_p}\frac{\partial H_p}{\partial t} = - \frac{\partial W_p}{\partial x} - \frac{f1(H_p,c_p,W_p)}{H_p}, [ \tex ]
[tex] \frac{1}{H_p}\frac{\partial}{\partial t}(H_p c_p} = - \frac{\partial}{\partial x}(W_p c_p) - \frac{f2(H_p,W_p,c_p)}{H_p}, [\tex]
[tex] 0 = f2(H_p,c_p,W_p) + f3(H_p,c_p,W_p). [\tex]

with the following conditions:
Hp(x,0) = 5
Wp(x,0) = s1(x)
cp(x,0) = s2(x)

Hp(0,t) = s3(t)
Wp(0,t) = W0
Wp(L,t) = 0
d(cp)/dx (L,t) = 0

How can I solve this numerically?
 
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  • #2
type "/tex" not "\tex" (or "$$") :wink:
ktsharp said:
I have the following system of partial differential algebraic equations:

[tex] \frac{1}{H_p}\frac{\partial H_p}{\partial t} = - \frac{\partial W_p}{\partial x} - \frac{f1(H_p,c_p,W_p)}{H_p}, [/tex]
[tex] \frac{1}{H_p}\frac{\partial}{\partial t}(H_p c_p) = - \frac{\partial}{\partial x}(W_p c_p) - \frac{f2(H_p,W_p,c_p)}{H_p}, [/tex]
[tex] 0 = f2(H_p,c_p,W_p) + f3(H_p,c_p,W_p). [/tex]
 
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  • #3
[UPDATED]

I have the following system of partial differential algebraic equations:

[tex] \frac{1}{H}\frac{\partial H}{\partial t} = - \frac{\partial W}{\partial x} - \frac{f_1(H,c,W)}{H}, [/tex]
[tex] \frac{1}{H}\frac{\partial}{\partial t}(H c) = - \frac{\partial}{\partial x}(W c) - \frac{f_2(H,W,c)}{H}, [/tex]
[tex] 0 = f_2(H,c,W) + f_3(H,c,W). [/tex]

with the following conditions:
H(x,0) = 5
W(x,0) = s1(x)
c(x,0) = s2(x)

H(0,t) = s3(t)
W(0,t) = W0
W(L,t) = 0
d(c)/dx (L,t) = 0

How can I solve this numerically?
 

1. How do you determine the eigenvalues of a system of PDAEs?

The eigenvalues of a system of PDAEs can be determined by solving the characteristic equation of the system. This equation is obtained by substituting the eigenvalue into the system of equations and setting the determinant of the resulting matrix equal to zero.

2. What is the significance of eigenvalues in solving a system of PDAEs?

Eigenvalues play a crucial role in solving a system of PDAEs as they determine the stability and behavior of the system. The system is stable if all eigenvalues have negative real parts, while the system is unstable if any eigenvalue has a positive real part.

3. How can I use eigenvalues to find the general solution of a system of PDAEs?

Once the eigenvalues have been determined, they can be substituted into the general solution of the system. This solution will contain terms that depend on the eigenvalues, and by varying the values of the eigenvalues, different solutions can be obtained.

4. Can I use numerical methods to solve a system of PDAEs with eigenvalues?

Yes, numerical methods such as the shooting method, finite difference method, or finite element method can be used to solve a system of PDAEs with eigenvalues. These methods involve discretizing the equations and solving the resulting system of algebraic equations.

5. Are there any software packages available for solving systems of PDAEs with eigenvalues?

Yes, there are several software packages available for solving systems of PDAEs with eigenvalues. Some popular options include MATLAB, Mathematica, and Python's SciPy library. These packages provide built-in functions for solving eigenvalue problems and can handle complex systems of PDAEs.

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