Coupling two weak forms

[Hasupama]

Hi,
I want to solve Poisson equation and continuity equation simultaneously. Weak forms are,

Weak_form_poisson = x[0]*( eps*phi.dx(i)*del_phi.dx(i) - e*(-Ne*del_phi )*dx
Weak_form_continuity= x[0]*( Ne-Ne0/Dt)*del_Ne - source*del_Ne )*dx

When I tried to solve these two together(Weak_form_poisson+Weak_form_continuity=0), It gives an error DIVERGED_FNORM_NAN

Is it incorrect to solve the addition of two weak forms?

Appreciate your suggestions on this problem. Thanks.

[connorjward]

Does it work if you solve for just one of those forms?

[dham]

There's really not enough information here to answer. The error indicates that the solver diverged, which is probably because the problem was ill-posed. That could either be because of a maths issue or because of a mistake translating that maths into code. Please post a minimal failing example (i.e. the shortest complete piece of code that illustrates the issue).

[colinjcotter]

What is x[0] ?

…

________________________________________ From: David A. Ham ***@***.***> Sent: 03 January 2024 10:18 To: firedrakeproject/firedrake Cc: Subscribed Subject: Re: [firedrakeproject/firedrake] Coupling two weak forms (Discussion #3301) There's really not enough information here to answer. The error indicates that the solver diverged, which is probably because the problem was ill-posed. That could either be because of a maths issue or because of a mistake translating that maths into code. Please post a minimal failing example (i.e. the shortest complete piece of code that illustrates the issue). — Reply to this email directly, view it on GitHub<#3301 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/ABOSV4QBEKKWA5W5VE7FDD3YMUV7LAVCNFSM6AAAAABBKJHFXGVHI2DSMVQWIX3LMV43SRDJONRXK43TNFXW4Q3PNVWWK3TUHM4DAMBRGM2TA>. You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[dham]

What are any of the symbols? That's why an MFE is needed.