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Solving DDE in Comsol.

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Hallo, I am modeling the Insulin therapies in Diabetes Mellitus, which gives rise to the Delay differential equations. I know that one can solve these equations in Matlab but I couldn't be able to find how can i solve it in Comsol. I would really appreciate if someone can help me out related to the said problem.

Thanking you in advance.

Regards,
Hari

2 Replies Last Post 30 avr. 2012, 18:27 UTC−4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 28 sept. 2011, 16:06 UTC−4
Hi

COMSOL is tailored to solve certain types of 2nd order PDE's entering either the general or the coefficient form (see the doc), you must reexpress your equations to enter one of the two forms, and if you have higher order you must add additional variables to reduce the equation set to only at most second order equations. Then you need the sufficient number of BC's (boundary conditions) as COMSOl will only solve correctly if you have ONE unique solution

Check the doc, and the "books", the one of Zimmermann is quite nice, unfortunately its written for te older v3.3, and not that evident to port to v4 (if you are starting)

--
Good luck
Ivar
Hi COMSOL is tailored to solve certain types of 2nd order PDE's entering either the general or the coefficient form (see the doc), you must reexpress your equations to enter one of the two forms, and if you have higher order you must add additional variables to reduce the equation set to only at most second order equations. Then you need the sufficient number of BC's (boundary conditions) as COMSOl will only solve correctly if you have ONE unique solution Check the doc, and the "books", the one of Zimmermann is quite nice, unfortunately its written for te older v3.3, and not that evident to port to v4 (if you are starting) -- Good luck Ivar

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Posted: 1 decade ago 30 avr. 2012, 18:27 UTC−4
Hi, I'm pretty sure you can't solve DDE in comsol, at least using versions till the 3.5
You may want to define additional state variables AND ordinary differential equations governing the time evolution of those, and define your convolution integral in terms of a combination of these states.
Hi, I'm pretty sure you can't solve DDE in comsol, at least using versions till the 3.5 You may want to define additional state variables AND ordinary differential equations governing the time evolution of those, and define your convolution integral in terms of a combination of these states.

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