Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.
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.
solute injection-advection dispersion equation
Posted 2011年5月14日 GMT-4 08:24 Porous Media Flow, Studies & Solvers Version 4.0a 2 Replies
Please login with a confirmed email address before reporting spam
Hi everyone, i am solving the 1d advection dispersion equation, i am asking how to insert a boundary condition at the top of a soil column: it is an injection of a solute flux (NaCl) every 30min. i tried to introduce a periodic function but in vain. Please help.
2 Replies Last Post 2011年5月15日 GMT-4 11:49
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hi
not easy to understand like that what is the true issue you have, is it how to make a periodic function (I would propose to use the rectangular pulse, as it has continuous smooth transitions, and modulate it with a "modulo" mod(t[1/s],Periode)
But then you might also have an issue with the solver settings, as the default "automatic" solver is not tailored fo repetitive changes in the BC, you should give the time steps, and impose a "strict" or an "intermediate" time stepping to ensure that the solver is not skipping over some of your NaCl injection pulses
--
Good luck
Ivar
not easy to understand like that what is the true issue you have, is it how to make a periodic function (I would propose to use the rectangular pulse, as it has continuous smooth transitions, and modulate it with a "modulo" mod(t[1/s],Periode)
But then you might also have an issue with the solver settings, as the default "automatic" solver is not tailored fo repetitive changes in the BC, you should give the time steps, and impose a "strict" or an "intermediate" time stepping to ensure that the solver is not skipping over some of your NaCl injection pulses
--
Good luck
Ivar
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Thank you for the answer,
the boudary condition that I want to introduce is a crenel function.
I tried to do that but only one pulse is detected, i am not sure that I used the "mod" properly please would you like to tell me how to use it exactally.
Thanks
the boudary condition that I want to introduce is a crenel function.
I tried to do that but only one pulse is detected, i am not sure that I used the "mod" properly please would you like to tell me how to use it exactally.
Thanks