lemonok

hello,
I have a problem in borehole simulation by adopting BHELoop.
I input the equal heating and cooling load by BHELoop by power method (BHE-dP) to single borehole.
but after one years operation, the soil temperature can not recovery to the initial value.
It is very strange, because if the extracted heat and injected heat is the same, after one yeas operation, the soil temperature should be back to its original temperature.
I ask for some help.
I results and setting is shown in the attachment.
Thank you very much for your help.

Thank you very much peter,
You are right, I have found this problem that if I use the constant time step, some point  non-convergence occurs, so the calculation jumps which leads some wrong results.
I will recheck the model itself, and use the automatic scheme, thank you so much.

Lemon

Thank you for your help.
I tried with the constant time step.  and also I tried with variable time step  with Forward Euler/Backward Euler...
I found if I use the constant time step, in some time point, there are no convergence, but it continues to run to the next time point.  however, for the variable time step, if there is no convergence, the operation will not  continue until the convergence is done. if there is no convergence, the wrong operation happens.
In fact, I compared the results get from the constant operation model and variable operation model. there are seems not big difference.
So what I am confusing is how to choose the time step. in what case the constant time step should be chosen, and when the variable time step is prefered?
Thank you for your help.
lemon

Hi, everyone
I am confused in time control method in simulation  process.
For the borehole system, I tried two time control method, one is constant time step method. The simulation could continue until the end of the time, but the results is not good.
I changed to automatic time step control via predictor-corrector scheme , but it could not continue simulate after one day. (I have 600?days to simulate), the time increment could not continue, error is always bigger than the tolerance. (shown in attached documents,), I do not know what happened .
I want to know what is the difference for the results calculated by these two time control method?
one more, I do not know what is the problem when I simulate by the automatic time step, Could some one help me ?
Thank you a lot

Thank you so much  Peter.  :D

Hi, Peter,
Thank you for all your answer, and may I ask what is BHE loop plug-in ? and how can I use it ?
Thank you a lot.
Lemon

Thank you very much Peter
Lemon

Hi,
if I define a single borehole, and I add an observation point in the node which I define it as the BHE before, what is the meaning of the observation point temperature? if it represent the borehole, why the temperature of that point is not equal to the temperature of the output of borehole?
Could anybody help me ? I am very confused ?
Thank you a lot for your kindly help .
lemon

Thank you very much for your kind reply, yes , now I understand your meaning. Thank you

hello,
in FeFLOW BHE is represent by a single point(P) see from  the surface , but I want to know should we design the mesh around  point P in such a way that the the distance from the around mesh points to point P meets the physical radius of borehole wall which we defined in BHE setting menu?
Thanks for your help