Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

Can't get the convergence for reaction included heat and mass transfer simulation

Please login with a confirmed email address before reporting spam

Hello everyone,

I added Laminar flow, Heat transfer in Fluitds and Transport of cencentrated species models in Comsol file. If there is no chemical reactions, the comsol can get convergence without effort. Now, I just add a simple irreversible reaction A--> B with simple reaction rate as r=k* c_A into Transport of cencentrated species. There are initial values, inflow(include A) and outflow modules in Transport of cencentrated species. The tolerance is 0.001. But the computing process get to be very weird. The error number goes down fast at first, then linearly slowly drops after 13 iterations. Even later the error number is smaller than the tolerance 0.001, the Comsol still can't get the convegence.

The computing seems like the following process: start of iteration number n, assemble , Solution, Stationary solver, Nonlinear solver go up, assmeble again, compute go up, start of interation number n+1. After convergence less than tolerance, solution drop from 99% to 18% sharply. After the iteration reaches to 100, the computing stops. Does anyone have clue why this happens? Like I need to change Solver options, or add module for reaction source in Transport of cencentrated species?

Thanks



0 Replies Last Post 5 mar 2021, 19:52 GMT-5
COMSOL Moderator

Hello D Zhang

Your Discussion has gone 30 days without a reply. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help.

If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base.

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.