Solving a system of second order tightly coupled nonlinear ODE with six initial conditions in Matlab









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I am solving a problem from fluid dynamics; in particular tightly coupled nonlinear ordinary differential equations. The following is a scaled-down version of my actual problem.
I have solved system of coupled odes many times in the past but this case is different since double derivatives of one variable depends on the double derivative of another variable. How do I implement it in ode45? I need 3 x 2 = 6 plots of x, x-dot and x-ddot versus time for t, 0 to 2. All required initial conditions have zero values.
enter image description here



Any help will be highly appreciated. If the ODEs had no last terms of double derivatives, I would have done it myself.










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  • I think this question fits better on math.stackexchange.com
    – rinkert
    Nov 11 at 17:54










  • Posted there, not of much help.
    – Vikash
    Nov 11 at 18:32










  • Or, can anyone please help me with the solution of a much simpler problem: postimg.cc/9z7LXg8B
    – Vikash
    Nov 12 at 9:15











  • Have you tried simply substituting the values for the second derivatives into the expressions? I suggest maybe trying a convenient change of variables, such as u=(x_1+x_2) and v=(x_1-x_2).
    – Joey Dumont
    Nov 12 at 17:01










  • I have solved the problem. Thank you all so much for helping me fix this problem. :)
    – Vikash
    Nov 13 at 15:16














up vote
0
down vote

favorite












I am solving a problem from fluid dynamics; in particular tightly coupled nonlinear ordinary differential equations. The following is a scaled-down version of my actual problem.
I have solved system of coupled odes many times in the past but this case is different since double derivatives of one variable depends on the double derivative of another variable. How do I implement it in ode45? I need 3 x 2 = 6 plots of x, x-dot and x-ddot versus time for t, 0 to 2. All required initial conditions have zero values.
enter image description here



Any help will be highly appreciated. If the ODEs had no last terms of double derivatives, I would have done it myself.










share|improve this question























  • I think this question fits better on math.stackexchange.com
    – rinkert
    Nov 11 at 17:54










  • Posted there, not of much help.
    – Vikash
    Nov 11 at 18:32










  • Or, can anyone please help me with the solution of a much simpler problem: postimg.cc/9z7LXg8B
    – Vikash
    Nov 12 at 9:15











  • Have you tried simply substituting the values for the second derivatives into the expressions? I suggest maybe trying a convenient change of variables, such as u=(x_1+x_2) and v=(x_1-x_2).
    – Joey Dumont
    Nov 12 at 17:01










  • I have solved the problem. Thank you all so much for helping me fix this problem. :)
    – Vikash
    Nov 13 at 15:16












up vote
0
down vote

favorite









up vote
0
down vote

favorite











I am solving a problem from fluid dynamics; in particular tightly coupled nonlinear ordinary differential equations. The following is a scaled-down version of my actual problem.
I have solved system of coupled odes many times in the past but this case is different since double derivatives of one variable depends on the double derivative of another variable. How do I implement it in ode45? I need 3 x 2 = 6 plots of x, x-dot and x-ddot versus time for t, 0 to 2. All required initial conditions have zero values.
enter image description here



Any help will be highly appreciated. If the ODEs had no last terms of double derivatives, I would have done it myself.










share|improve this question















I am solving a problem from fluid dynamics; in particular tightly coupled nonlinear ordinary differential equations. The following is a scaled-down version of my actual problem.
I have solved system of coupled odes many times in the past but this case is different since double derivatives of one variable depends on the double derivative of another variable. How do I implement it in ode45? I need 3 x 2 = 6 plots of x, x-dot and x-ddot versus time for t, 0 to 2. All required initial conditions have zero values.
enter image description here



Any help will be highly appreciated. If the ODEs had no last terms of double derivatives, I would have done it myself.







matlab numerical-methods ode scientific-computing numerical-integration






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share|improve this question













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edited Nov 11 at 17:59

























asked Nov 11 at 16:25









Vikash

319




319











  • I think this question fits better on math.stackexchange.com
    – rinkert
    Nov 11 at 17:54










  • Posted there, not of much help.
    – Vikash
    Nov 11 at 18:32










  • Or, can anyone please help me with the solution of a much simpler problem: postimg.cc/9z7LXg8B
    – Vikash
    Nov 12 at 9:15











  • Have you tried simply substituting the values for the second derivatives into the expressions? I suggest maybe trying a convenient change of variables, such as u=(x_1+x_2) and v=(x_1-x_2).
    – Joey Dumont
    Nov 12 at 17:01










  • I have solved the problem. Thank you all so much for helping me fix this problem. :)
    – Vikash
    Nov 13 at 15:16
















  • I think this question fits better on math.stackexchange.com
    – rinkert
    Nov 11 at 17:54










  • Posted there, not of much help.
    – Vikash
    Nov 11 at 18:32










  • Or, can anyone please help me with the solution of a much simpler problem: postimg.cc/9z7LXg8B
    – Vikash
    Nov 12 at 9:15











  • Have you tried simply substituting the values for the second derivatives into the expressions? I suggest maybe trying a convenient change of variables, such as u=(x_1+x_2) and v=(x_1-x_2).
    – Joey Dumont
    Nov 12 at 17:01










  • I have solved the problem. Thank you all so much for helping me fix this problem. :)
    – Vikash
    Nov 13 at 15:16















I think this question fits better on math.stackexchange.com
– rinkert
Nov 11 at 17:54




I think this question fits better on math.stackexchange.com
– rinkert
Nov 11 at 17:54












Posted there, not of much help.
– Vikash
Nov 11 at 18:32




Posted there, not of much help.
– Vikash
Nov 11 at 18:32












Or, can anyone please help me with the solution of a much simpler problem: postimg.cc/9z7LXg8B
– Vikash
Nov 12 at 9:15





Or, can anyone please help me with the solution of a much simpler problem: postimg.cc/9z7LXg8B
– Vikash
Nov 12 at 9:15













Have you tried simply substituting the values for the second derivatives into the expressions? I suggest maybe trying a convenient change of variables, such as u=(x_1+x_2) and v=(x_1-x_2).
– Joey Dumont
Nov 12 at 17:01




Have you tried simply substituting the values for the second derivatives into the expressions? I suggest maybe trying a convenient change of variables, such as u=(x_1+x_2) and v=(x_1-x_2).
– Joey Dumont
Nov 12 at 17:01












I have solved the problem. Thank you all so much for helping me fix this problem. :)
– Vikash
Nov 13 at 15:16




I have solved the problem. Thank you all so much for helping me fix this problem. :)
– Vikash
Nov 13 at 15:16

















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