Solve DAEs in MATLAB | Omar Bin Yusuf

[oby7842]

I have problem in solving following DAE's:

1. 0 = X*U1*C4+X*U2*C4 - 1

2. Re*C1*(U1+U2)*U1' +Re*C2*(U1^2+U2)*U2'= X*(U1*C2+U1*U2+U2*C3)+(1/X)*(U1+U2)

here X is the independent variable and U1 and U2 depend on X and others are constants.I need to solvethis DAE's in matlab. To solve in MATLAB i have following Mass matrix and function:

M=[0 0 ; Re*C1*(U(1)+U(2)) Re*C2*(U(1)^2+U(2))]; U'=[U(1)' ; U(2)'] ;

f = [ X*U1*C4+X*U2*C4 - 1 ; X*(U1*C2+U1*U2+U2*C3)+(1/X)*(U1+U2) ];

can you give me any suggestion how can I solve this problem in matlab? I will appreciate any kind of suggestion in this regard. I would be grateful also if I get any kind of hints to solve the Mass matrix. thanks for reading my problem.

Omar Bin Yusuf

 

[vishal007win]

go thru MATLAB help..its explicitly given there
i think ode15 or ode23 will suit ur purpose..

 

[oby7842]

yeah in MATLAB help its says that ode15s can solve this type DAE's. But my Mass matrix M is dependent of U(dependent variable)...I have example to solve this type of problem when Mass matrix is constant. But how can I evaluate value of M?

 

[vishal007win]

i prefer using ode45 for dat...

 

[oby7842]

Can you please elaborate the idea a bit?? It will be a great help for me. thanks