Cause the high error in my model?

hamidciv · April 3, 2015, 08:41

hi dear glenn
i considered variety of initial condition & boindary condition, unfortunately the same error as your mentioned appear :
(A wall has been placed at portion(s) of an OUTLET)

Inevitably now i runned with consider u, when my run ended, i express my result, if your possible please guide me that What is the cause of the error in my model in your opinion?
thanks in advance

ghorrocks · April 6, 2015, 19:13

"A wall has been placed...." is not an error. It is a warning. If you are happy with the situation you can proceed.

You should consider changing the boundary to an opening.

hamidciv · April 7, 2015, 06:03

hi dear glenn
after the warning "a wall has been placed ......" my run be stopped with errors i attached in previous post, in your opinion Which boundary i can changed? i consider variety of boundary conditions but unfortunately i countered with the same warning and finally get error, For several days I have runnig with consider u=0 and apply your orders & suggestions, in time steps 250 of 400 Fortunately I have seen in my upstream flow weirdness removed, after the end of run i express result of run in here, i hope percentage of error in my model be low.

Thanks in advance for spending time and follw up.

ghorrocks · April 7, 2015, 21:26

Have a look at the outlet boundary it is talking about. If the small amount of backflow the warning is talking about is insignificant then do not worry about it and proceed. If it is a problem then some options are:
* Change to an opening boundary
* Move the boundary further downstream

hamidciv · April 8, 2015, 08:27

hi dear glenn
unfortunately i dont exactly understand of small amount?
Smaller than what amount is small amount and i can ignore it? my mean is a specific criterion for small amount,whether should it be considered with regard length of geometry? in my model after the warning as shown follow , my run be stopped, whether in your opinion amount of backflow is high in my model which stopped my running or cause of error is another thing?
i attached warning in follow.
I really appreciate your help.

ghorrocks · April 8, 2015, 17:56

You have to work out if it is significant or not. I have no idea what you are trying to do or how accurate you need to be. Only you know that. So you have to look at the results you have and the effect this will have on it and make a judgement about whether it is significant.

hamidciv · April 10, 2015, 09:42

ok i after check my result and compared with experimental data, express my result in here.
i really thanks for help me and spending your time.
best regards

April 3, 2015, 08:41		#21
hamidciv Senior Member Hydreaulic structures Join Date: Sep 2012 Posts: 283 Rep Power: 14	hi dear glenn i considered variety of initial condition & boindary condition, unfortunately the same error as your mentioned appear : (A wall has been placed at portion(s) of an OUTLET) Inevitably now i runned with consider u, when my run ended, i express my result, if your possible please guide me that What is the cause of the error in my model in your opinion? thanks in advance Last edited by hamidciv; April 10, 2015 at 09:45.

April 6, 2015, 19:13		#22
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	"A wall has been placed...." is not an error. It is a warning. If you are happy with the situation you can proceed. You should consider changing the boundary to an opening. hamidciv likes this.

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April 7, 2015, 06:03		#23
hamidciv Senior Member Hydreaulic structures Join Date: Sep 2012 Posts: 283 Rep Power: 14	hi dear glenn after the warning "a wall has been placed ......" my run be stopped with errors i attached in previous post, in your opinion Which boundary i can changed? i consider variety of boundary conditions but unfortunately i countered with the same warning and finally get error, For several days I have runnig with consider u=0 and apply your orders & suggestions, in time steps 250 of 400 Fortunately I have seen in my upstream flow weirdness removed, after the end of run i express result of run in here, i hope percentage of error in my model be low. Thanks in advance for spending time and follw up.

April 7, 2015, 21:26		#24
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	Have a look at the outlet boundary it is talking about. If the small amount of backflow the warning is talking about is insignificant then do not worry about it and proceed. If it is a problem then some options are: * Change to an opening boundary * Move the boundary further downstream

April 8, 2015, 17:56		#26
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	You have to work out if it is significant or not. I have no idea what you are trying to do or how accurate you need to be. Only you know that. So you have to look at the results you have and the effect this will have on it and make a judgement about whether it is significant.

April 10, 2015, 09:42		#27
hamidciv Senior Member Hydreaulic structures Join Date: Sep 2012 Posts: 283 Rep Power: 14	ok i after check my result and compared with experimental data, express my result in here. i really thanks for help me and spending your time. best regards