Discussion Forum

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