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Boundary Condition
Posted Jun 20, 2012, 4:50 a.m. EDT Porous Media Flow Version 4.3 2 Replies
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Hi,
I want to use this expression as a boundary condition (pressure head) in the Richard's equation modules
Hp0=1.094-y+0.235*cos(0.0081*t)
where, t is the time and y is the vertical coordinate.
I want to use above expression whenever is positive and if it is negative put zero for Hp0.
I have tried to use 'the if operator' but it has not worked.How can I do that in the COMSOL?
Thanks in advance
Amir
I want to use this expression as a boundary condition (pressure head) in the Richard's equation modules
Hp0=1.094-y+0.235*cos(0.0081*t)
where, t is the time and y is the vertical coordinate.
I want to use above expression whenever is positive and if it is negative put zero for Hp0.
I have tried to use 'the if operator' but it has not worked.How can I do that in the COMSOL?
Thanks in advance
Amir
2 Replies Last Post Jun 20, 2012, 11:49 p.m. EDT
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Posted:
1 decade ago
Hi
have you tried the max() operator ?
Or a boolean (...)*(...>0)
but both of these have discontinuities that might well mike your solver have convergion issues
--
Good luck
Ivar
have you tried the max() operator ?
Or a boolean (...)*(...>0)
but both of these have discontinuities that might well mike your solver have convergion issues
--
Good luck
Ivar
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Posted:
1 decade ago
Hi
Thank you for your response
yes I have tried both of them but they did not work properly.
1.094-y+0.235[m]*cos(0.0081[1/s]*t)*(y<=1.094)
OR
If ((1.094-y+0.235[m]*cos(0.0081[1/s]*t))<=0,0,(1.094-y+0.235[m]*cos(0.0081[1/s]*t))
The boundary condition is a linear function of y but when I use those operator the result is not linear (the line graph of the boundary ).
Another question is that when we turn on the gravity effects on Darcy's low or Richard's modules, the gravity effects acts as hydrostatic pressure or has other effects on the model?
The size of my model is a bit large (22Mb) and I can't attache it.
Would you please guide me to overcome this issue?
Regards,
Amir
Thank you for your response
yes I have tried both of them but they did not work properly.
1.094-y+0.235[m]*cos(0.0081[1/s]*t)*(y<=1.094)
OR
If ((1.094-y+0.235[m]*cos(0.0081[1/s]*t))<=0,0,(1.094-y+0.235[m]*cos(0.0081[1/s]*t))
The boundary condition is a linear function of y but when I use those operator the result is not linear (the line graph of the boundary ).
Another question is that when we turn on the gravity effects on Darcy's low or Richard's modules, the gravity effects acts as hydrostatic pressure or has other effects on the model?
The size of my model is a bit large (22Mb) and I can't attache it.
Would you please guide me to overcome this issue?
Regards,
Amir