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Mathematics Global ODEs and DAEs: How to port ODEs system from Mathcad?

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Hi, I have the following system of ODEs in Mathcad:

It does solve well in Mathcad, however when I try to port it to COMSOL - the results are flat lines (equal to initial conditions).

Here is how I write the equations above in COMSOL using 0D 'Global ODEs and DAEs':

ro/(2*pi)*Stt*log(pi^0.5*lk/S^0.5)-p-ro/(8*pi*S)*St^2

1/(gamma-1)*pt-(N(t)-lk*gamma/(gamma-1)*p*St)/lk*S

Where N(t) - is lineary interpolated table function. Initial conditions: p(0) = 2000000, S(0)=1.5*10^-7, S'(0) = 0. The time range is: range(0, 1.0e-7, 4.4e-5).

Like I said above, the results are wrong (flat lines at the level of initial conditions).

Please advise what is wrong here. Maybe some issue with equations form, etc. Thank you.


0 Replies Last Post Jun 22, 2018, 7:03 p.m. EDT
COMSOL Moderator

Hello Alex Dox

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