MATLAB Solve DAEs in MATLAB | Omar Bin Yusuf

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SUMMARY

The discussion focuses on solving differential-algebraic equations (DAEs) in MATLAB, specifically using the functions ode15s and ode45. Omar Bin Yusuf presents a system of DAEs involving variables U1 and U2, with a mass matrix M dependent on these variables. The key takeaway is that while ode15s is suitable for solving DAEs, the challenge lies in evaluating the mass matrix M, which varies with the dependent variables. The conversation emphasizes the need for clarification on how to handle this dependency in MATLAB.

PREREQUISITES
  • Understanding of differential-algebraic equations (DAEs)
  • Familiarity with MATLAB programming
  • Knowledge of MATLAB functions ode15s and ode45
  • Concept of mass matrices in numerical methods
NEXT STEPS
  • Research how to implement time-dependent mass matrices in MATLAB
  • Learn about the specific syntax and options for ode15s in MATLAB
  • Explore examples of solving DAEs with variable mass matrices
  • Investigate the differences between ode15s and ode45 for solving DAEs
USEFUL FOR

This discussion is beneficial for MATLAB users, particularly engineers and researchers working with differential-algebraic equations, as well as anyone looking to understand the implementation of variable mass matrices in numerical simulations.

oby7842
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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
 
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go thru MATLAB help..its explicitly given there
i think ode15 or ode23 will suit ur purpose..
 
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?
 
i prefer using ode45 for dat...
 
Can you please elaborate the idea a bit?? It will be a great help for me. thanks
 

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