Ivar KJELBERG
COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted:
1 decade ago
04.03.2010, 14:58 GMT-5
Hi
I believe you have the segregated solver too that should allow you to separate somewhat the solving processwhile keeping them linked, no ?
and further I do not really understand why you cannot set a non zero initial condition for "u" ("u" being the generic name for "u_esld" in that application mode).
Bit I'm not sure I understood everything from your comments (as I do no have the Earth Science) I have tried to reproduce the effect by similarity but I'm not sure I have managed
Good luck
Ivar
Hi
I believe you have the segregated solver too that should allow you to separate somewhat the solving processwhile keeping them linked, no ?
and further I do not really understand why you cannot set a non zero initial condition for "u" ("u" being the generic name for "u_esld" in that application mode).
Bit I'm not sure I understood everything from your comments (as I do no have the Earth Science) I have tried to reproduce the effect by similarity but I'm not sure I have managed
Good luck
Ivar
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Posted:
1 decade ago
04.03.2010, 15:11 GMT-5
Ivar,
Correct, the segregated solver will keep them linked but should not be necessary (I believe) for this staionary problem.
Essentially, I have two stationary PDEs, connected by the velocity (the resulting dependent variable from the Darcy's Law setup). The transport advection dispersion equation uses this variable (u_esdl). Solving separately, using the segregated solver or by hand, should not be necessary since, I believe, Comsol should be able to find u_esdl while solving for c_esst. And, this is true since it works when I add the epsilon to by velocity, 'u_esdl+esp', in my transport module.
>>and further I do not really understand why you cannot set a non zero initial condition for "u" ("u" being the generic name for "u_esld" in that application mode).
Exactly. How do I explicitly set an initial condition for u_esdl?
Kevin
Ivar,
Correct, the segregated solver will keep them linked but should not be necessary (I believe) for this staionary problem.
Essentially, I have two stationary PDEs, connected by the velocity (the resulting dependent variable from the Darcy's Law setup). The transport advection dispersion equation uses this variable (u_esdl). Solving separately, using the segregated solver or by hand, should not be necessary since, I believe, Comsol should be able to find u_esdl while solving for c_esst. And, this is true since it works when I add the epsilon to by velocity, 'u_esdl+esp', in my transport module.
>>and further I do not really understand why you cannot set a non zero initial condition for "u" ("u" being the generic name for "u_esld" in that application mode).
Exactly. How do I explicitly set an initial condition for u_esdl?
Kevin
Ivar KJELBERG
COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
05.03.2010, 08:48 GMT-5
Hi
For me he segregated solver eases (and shortenes) the solving in many cases, that is why I like to use it, it also forces me to think which part of the system isthe most stable and should be treated first.
They way I understand is that when you define the "init" and derivatives "dinit" of "u" they are later copied into the application specific name "u_whatever" during the solving preparation. One way to check is to do first a "Solve - Get initial value" and check by postprocessing that these are coherent.
Good luck
Ivar
Hi
For me he segregated solver eases (and shortenes) the solving in many cases, that is why I like to use it, it also forces me to think which part of the system isthe most stable and should be treated first.
They way I understand is that when you define the "init" and derivatives "dinit" of "u" they are later copied into the application specific name "u_whatever" during the solving preparation. One way to check is to do first a "Solve - Get initial value" and check by postprocessing that these are coherent.
Good luck
Ivar
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Posted:
1 decade ago
05.03.2010, 09:32 GMT-5
Hi,
The segregated solver doesn't increase solver efficiency in this case. However, I can understand how there would be many cases where it makes more sense to do this.
Again, my question is how do I set 'init' for 'u'? 'u' is just a parameter and I haven't been able to find where I can set the initial value for a parameter. There are many examples of setting the initial value for dependent variables (in this case 'p' and 'c' are the dependent variables, respectively, for the Darcy and transport modules).
Thanks,
Kevin
Hi,
The segregated solver doesn't increase solver efficiency in this case. However, I can understand how there would be many cases where it makes more sense to do this.
Again, my question is how do I set 'init' for 'u'? 'u' is just a parameter and I haven't been able to find where I can set the initial value for a parameter. There are many examples of setting the initial value for dependent variables (in this case 'p' and 'c' are the dependent variables, respectively, for the Darcy and transport modules).
Thanks,
Kevin