Hi,

There are problems of stability.
You should check the model before running it.

I suggest a couple of checks:

 at first run the model in steady state and check if it converges and that the
balance (IN-OUT) is fine for your problem, otherwise you have to control your
input, the number of layers vs deep, mesh etc
then I would rehash the steady state solution and I would run the new model in
transient conditionif that does not work, I would check again the mesh near well
points and verify how the model works without wells.Hoping this will help you!

Don't quit!

Giovanna Monti
environmental engineer
Washington DC


--- Mer 13/5/09, manish_cjonty2006 <manish_cjonty2006@...> ha scritto:

Da: manish_cjonty2006 <manish_cjonty2006@...>
Oggetto: [feflow] to reduce model run time
A: feflow@...
Data: Mercoledì 13 maggio 2009, 12:42


Hello everyone...

I am doing groundwater flow and contaminant transport modeling for saturated
region with transient conditions. I am doing it for 1.0xE4 years. while doing
that i am facing two problems

1.Head values at some of the observation wells are oscillating 10-15 metres

2.Time step is not going beyond 200 days so it is taking so much time for
running. I am using automatic predictor corrector method.

i would like you all to give your suggestions so that i can resolve thee
problems.

Thanks.

Regards,
Manish Chopra

Hi Pete,

Thank you for your answer. Actually I should have done a mistake and
some confusion.

You are absolutely right. A seepage boundary condition is constrained
and the constrains work as I want. Initially I assigned an atmospheric
pressure (constrained) along the angled hole. Using the automatic tool
for the definition of a seepage boundary, I basically assigned a total
head equal to the elevation of each node of the hole. But the hole is
angled, then I automatically assigned a different total head (equal to
the elevation of each single node) along the angled hole. This
situation was making me crazy because I was obtaining nonsense
results. Then I realized that I had to use a constant head value along
the drainage hole (the highest elevation of the hole) and it made more
sense at the end.

Giovanni


On Mon, May 11, 2009 at 8:54 PM, Pete Sinton <psinton@...> wrote:
> Hi Giovanni,
>
> I think FEFLOW 5.3 shuts off discrete features in the UZ, but you should
> check with WASY about later versions.
>
> It should work if you constrain the discharge node to stop any outflow
> if the head at the node is lower than the elevation of the exit point of
> the borehole. I think a head-constrained cauchy node should work.
>
>
> *Pete Sinton*
>
> www.aquageo.us
>
>
>
> Giovanni Firmani wrote:
>>
>>
>> Dear all,
>>
>> I am dealing with a 2D transient and unsaturated model for
>> depressurization purposes. The client asked me to evaluate the effect
>> of horizontal drainage holes that I simulated as a seepage boundary.
>> In the same time I have been asked to do the same thing with inclined
>> ((below the horizontal line) drainage holes. I was wondering if in
>> this case the seepage boundary condition can be applied or not.
>> According to me, such holes should work as the horizontal ones as long
>> as the elevation of the water table is above the elevation of the
>> highest point of the hole, but when the hole becomes partially
>> unsaturated water can come out from the hole because the gradient is
>> not great enough. Using the seepage boundary condition then,
>> overestimates the volume coming out from the model.
>>
>> I was thinking to simulate it as an high conductive feature using the
>> "discrete element feature" tool, simulatin this condition as a very
>> permeable fault. Can the discrete element feature be used in an
>> unsaturated model ? As my holes progress with time can I generate a
>> power function for the property of a discrete element like a fault?
>>
>> thank you
>> Giovanni

Hi Marielena Lucen.....
 
Sorry for replying so late. I am having some case studies which i have done
using FEFLOW. If you are still in need of those, let me know. i will send those
to you.
 
Regards,
Manish Chopra 



--- On Thu, 19/2/09, marielenalucen <malenalucen@...> wrote:


From: marielenalucen <malenalucen@...>
Subject: [feflow] applications of feflow
To: feflow@...
Date: Thursday, 19 February, 2009, 8:13 AM

hi everybody

i desperate need a tutorial or some applications or examples using
feflow, please if some have a file in pdf or word about this please
send it to malenalucen@ gmail.com

Thank you

Marielena Lucen
Hydraulic Engineer
Peru

Hello everyone...

I am doing groundwater flow and contaminant transport modeling for saturated
region with transient conditions. I am doing it for 1.0xE4 years. while doing
that i am facing two problems

1.Head values at some of the observation wells are oscillating 10-15 metres

2.Time step is not going beyond 200 days so it is taking so much time for
running. I am using automatic predictor corrector method.

i would like you all to give your suggestions so that i can resolve thee
problems.

Thanks.

Regards,

Manish Chopra

Hi Giovanni,

I think FEFLOW 5.3 shuts off discrete features in the UZ, but you should
check with WASY about later versions.

It should work if you constrain the discharge node to stop any outflow
if the head at the node is lower than the elevation of the exit point of
the borehole. I think a head-constrained cauchy node should work.


*Pete Sinton*

www.aquageo.us



Giovanni Firmani wrote:
>
>
> Dear all,
>
> I am dealing with a 2D transient and unsaturated model for
> depressurization purposes. The client asked me to evaluate the effect
> of horizontal drainage holes that I simulated as a seepage boundary.
> In the same time I have been asked to do the same thing with inclined
> ((below the horizontal line) drainage holes. I was wondering if in
> this case the seepage boundary condition can be applied or not.
> According to me, such holes should work as the horizontal ones as long
> as the elevation of the water table is above the elevation of the
> highest point of the hole, but when the hole becomes partially
> unsaturated water can come out from the hole because the gradient is
> not great enough. Using the seepage boundary condition then,
> overestimates the volume coming out from the model.
>
> I was thinking to simulate it as an high conductive feature using the
> "discrete element feature" tool, simulatin this condition as a very
> permeable fault. Can the discrete element feature be used in an
> unsaturated model ? As my holes progress with time can I generate a
> power function for the property of a discrete element like a fault?
>
> thank you
> Giovanni

Dear all,

I am dealing with a 2D transient and unsaturated model for
depressurization purposes. The client asked me to evaluate the effect
of horizontal drainage holes that I simulated as a seepage boundary.
In the same time I have been asked to do the same thing with inclined
((below the horizontal line) drainage holes. I was wondering if in
this case the seepage boundary condition can be applied or not.
According to me, such holes should work as the horizontal ones as long
as the elevation of the water table is above the elevation of the
highest point of the hole, but when the hole becomes partially
unsaturated water can come out from the hole because the gradient is
not great enough. Using the seepage boundary condition then,
overestimates the volume coming out from the model.

I was thinking to simulate it as an high conductive feature using the
"discrete element feature" tool, simulatin this condition as a very
permeable fault. Can the discrete element feature be used in an
unsaturated model ? As my holes progress with time can I generate a
power function for the property of a discrete element like a fault?

thank you
Giovanni

Dear Colleagues

A PhD student who is looking into geothermal possibilities at a location and who
has collected a lot of data has contacted us.

He needs to analyse the data with a groundwater modelling package called FEFLOW.
However, this is too expensive for him to buy based on his likely useage.

Could you suggest a means whereby he could undertake his analysis without
purchase of a licence as after the analysis it appears unlikely he will require
it for much ongoing work.

Many Thanks, All advice appreciated

Dr John C Bullas MIHT FGS
Southamton
UK

Hi Mr. Giovanni

My model is saturated transient flow and contaminant transport with one river
with transfer boundary conditions. Others boundary conditions are constant only.
Most of the observation points are far away from the river.


-- In feflow@..., Giovanni Firmani <g.firmani@...> wrote:
>
> it is hard to understand if it is problem or not. Can you provide more
> details of your model? transient or steady? and in the first case are the
> BCs transient ? Saturated or unsaturated model? are you using the re-wetting
> capabilities (sometimes it could give some oscillations problems).
>
> Oscillations can also depend on other stresses of the model. maybe your
> observation point is close to a river that was defined with transient
> conditions... there are several reasons for oscillations. Try to be more
> specific.
>
> gio
>
>
> On Thu, Apr 23, 2009 at 3:15 PM, manish_cjonty2006 <
> manish_cjonty2006@...> wrote:
>
> > Hi
> >
> > I am facing a problem in feflow. It is when i am running my problem, the
> > graph of head values at various observation points is showing too many
> > oscillations in head values. Is anything wrong with that or it is just ok?
>

Hi Manish,

Oscillations are common especially in complex models; whether they are
important depends on the whether the oscillations decrease to values
small enough to be of no concern and also if the mass balance of the
model is acceptable (eg small compared to total inflows and outflows).

*Pete*
www.aquageo.us



manish_cjonty2006 wrote:
>
>
> Hi
>
> I am facing a problem in feflow. It is when i am running my problem,
> the graph of head values at various observation points is showing too
> many oscillations in head values. Is anything wrong with that or it is
> just ok?

it is hard to understand if it is problem or not. Can you provide more
details of your model? transient or steady? and in the first case are the
BCs transient ? Saturated or unsaturated model? are you using the re-wetting
capabilities (sometimes it could give some oscillations problems).

Oscillations can also depend on other stresses of the model. maybe your
observation point is close to a river that was defined with transient
conditions... there are several reasons for oscillations. Try to be more
specific.

gio


On Thu, Apr 23, 2009 at 3:15 PM, manish_cjonty2006 <
manish_cjonty2006@...> wrote:

> Hi
>
> I am facing a problem in feflow. It is when i am running my problem, the
> graph of head values at various observation points is showing too many
> oscillations in head values. Is anything wrong with that or it is just ok?

Hi

I am facing a problem in feflow. It is when i am running my problem, the graph
of head values at various observation points is showing too many oscillations in
head values. Is anything wrong with that or it is just ok?

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hi

	 Our team are working at a project on seawater intrusion in China, and
its the time to choose a proper software. Feflow, as our first choise,
is definitely the  most powerful and reliable one but I still have
some wonders may be you can help me with.

	 Our project this time including a information system (manage the sea
water data, developed through the ARCgis engine) and we want to add
several simulation models in to this system, I mean after we establish
the simulation models, we want to use feflow to do the calculations in
our integrated user interface rather than in feflow itself, and of
course the results have to be given in our system. As I know there is
no SDK in 5.3 or eailer.

You should find find all you need at this web site:

http://www.feflow.info/26.html

*Pete *
www.aquageo.us


Marielena Lucen wrote:
>
> Hi giovanni
>
> Thank you but i do not have de cd program, so if you are so afable and
> send
> me the exercise I will be very thankful with you
>
> Bye
> Malena Lucen
>
> 2009/2/18 Giovanni Firmani <g.firmani@...
> <mailto:g.firmani%40gmail.com>>
>
> > In the program folder you can find examples and exercises:
> >
> > C:\Program Files\WASY\FEFLOW 5.3\demo
> >
> > while in the Installing dvd you can find all the manuals and in
> > particular the tutorial for the demo example exercise:
> >
> > E:\doc\demo_exercise.pdf
> >
> > there is also a Spanish version in my dvd
> >
> > E:\doc\demo_exercise_espanol.pdf
> >
> > Ciao
> > gio
> >
> >
> > On Thu, Feb 19, 2009 at 11:43 AM, marielenalucen
> <malenalucen@...
> <mailto:malenalucen%40gmail.com><malenalucen%40gmail.com>>
> > wrote:
> > > hi everybody
> > >
> > > i desperate need a tutorial or some applications or examples using
> > > feflow, please if some have a file in pdf or word about this please
> > > send it to malenalucen@... <mailto:malenalucen%40gmail.com>
> <malenalucen%40gmail.com>
> > >
> > > Thank you
> > >
> > > Marielena Lucen
> > > Hydraulic Engineer
> > > Peru

Hi giovanni

Thank you but i do not have de cd program, so if you are so afable and send
me the exercise I will be very thankful with you

Bye
Malena Lucen


2009/2/18 Giovanni Firmani <g.firmani@...>

>   In the program folder you can find examples and exercises:
>
> C:\Program Files\WASY\FEFLOW 5.3\demo
>
> while in the Installing dvd you can find all the manuals and in
> particular the tutorial for the demo example exercise:
>
> E:\doc\demo_exercise.pdf
>
> there is also a Spanish version in my dvd
>
> E:\doc\demo_exercise_espanol.pdf
>
> Ciao
> gio
>
>
> On Thu, Feb 19, 2009 at 11:43 AM, marielenalucen
<malenalucen@...<malenalucen%40gmail.com>>
> wrote:
> > hi everybody
> >
> > i desperate need a tutorial or some applications or examples using
> > feflow, please if some have a file in pdf or word about this please
> > send it to malenalucen@... <malenalucen%40gmail.com>
> >
> > Thank you
> >
> > Marielena Lucen
> > Hydraulic Engineer
> > Peru

In the program folder you can find examples and exercises:

C:\Program Files\WASY\FEFLOW 5.3\demo

while in the Installing dvd you can find all the manuals and in
particular the tutorial for the demo example exercise:

E:\doc\demo_exercise.pdf

there is also a Spanish version in my dvd

E:\doc\demo_exercise_espanol.pdf

Ciao
gio


On Thu, Feb 19, 2009 at 11:43 AM, marielenalucen <malenalucen@...> wrote:
> hi everybody
>
> i desperate need a tutorial or some applications or examples using
> feflow, please if some have a file in pdf or word about this please
> send it to malenalucen@...
>
> Thank you
>
> Marielena Lucen
> Hydraulic Engineer
> Peru

hi everybody

i desperate need a tutorial or some applications or examples using
feflow, please if some have a file in pdf or word about this please
send it to malenalucen@...

Thank you

Marielena Lucen
Hydraulic Engineer
Peru

Thanks Pete.

You are right, I figured out that Feflow interpolates the values at
t=0 and t=730. As you said the only way to switch off the 1st boundary
condition is to use the constrains. I my case it was easy cause I was
simulating a time variant seepage condition (some horizontal holes
built in different periods) and from 0 to 729 I assumed a fake
head=999 with the constrain in the maximum flow (=0).

Thank you very much. I had a confimation I have done the right thing though !

Gio


On Sun, Feb 15, 2009 at 3:18 AM, Pete Sinton <psinton@...> wrote:
> Hi Gio,
>
> I searched my notes and manuals about this and came up with nothing.  In
> all the examples I've seen, the first time is always zero, and I have
> been in habit of setting up my power functions this way for a long
> time.  I don't remember what FEFLOW assumes for a situation like you
> describe, but my guess is that it will either use the value at time 730
> for the value at time 0 or will set the value to 0 at time 0 and
> interpolate between time 0 and time 730.
>
> There is no direct way of "turning off" (deactivating) a boundary
> condition  (BC) within a single feflow model, unless you use the
> SwitchBC module which you'd have to get from WASY.  In some cases a BC
> node can be deactivated using BC constraints, but this will not always
> work (especially as the model complexity or number of such constraints
> increases).  You can also deactivate a BC by using two feflow models,
> one that simulates a portion of time without the BC, and one set up with
> it.  The first model would be used to initialize the second.  Run a
> model from zero to 730 without the BC, use the result to initialize a
> second model that has the time varying BC.
>
> Pete

Hi Gio,

I searched my notes and manuals about this and came up with nothing.  In
all the examples I've seen, the first time is always zero, and I have
been in habit of setting up my power functions this way for a long
time.  I don't remember what FEFLOW assumes for a situation like you
describe, but my guess is that it will either use the value at time 730
for the value at time 0 or will set the value to 0 at time 0 and
interpolate between time 0 and time 730.

There is no direct way of "turning off" (deactivating) a boundary
condition  (BC) within a single feflow model, unless you use the
SwitchBC module which you'd have to get from WASY.  In some cases a BC
node can be deactivated using BC constraints, but this will not always
work (especially as the model complexity or number of such constraints
increases).  You can also deactivate a BC by using two feflow models,
one that simulates a portion of time without the BC, and one set up with
it.  The first model would be used to initialize the second.  Run a
model from zero to 730 without the BC, use the result to initialize a
second model that has the time varying BC.

Pete


Giovanni Firmani wrote:
>
> Pete,
> I have a terrible doubt now. If I define a power function (for a head
> boundary condition for example) file like the following one
>
> !
> ! t [d] fvalue
> !---------------------
> 730 334
> 1460 334
>
> does it mean that the head boundary condition is off between 0 and
> 730? Running the model I noticed that is not like that but if I do not
> want the boundary condition ON I have to use a fake head and a
> constrain that is able to disable it between 0 and 730.
>
> Giovanni
>
> On Sun, Feb 8, 2009 at 12:59 PM, Pete Sinton <psinton@...
> <mailto:psinton%40aquageo.us>> wrote:
> > Hi Gio,
> >
> > Yes, that works. I find it convoluted and cumbersome, so I resort to
> > bypassing feflow's interface. I know I will get what I want.
> >
> > Glad to hear you solved the problem
> >
> > Cheers
> >
> > --
> >
> > Pete Sinton
> >
> > Principal Hydrogeologist
> >
> > AquaGeo, Ltd.
> >
> > 11560 Penny Rd
> >
> > Conifer CO 80433
> >
> > Cell 720.841.5526
> >
> > Phone 303.838.7863
> >
> > psinton@... <mailto:psinton%40aquageo.us>
> >
> > www.aquageo.us
> >
> > This e-mail together with any attachments is confidential and may be the
> > subject of legal privilege. If you are not the intended recipient,
> you are
> > not permitted to print, copy, disclose or use the content or
> attachments in
> > any way. AquaGeo, Ltd. respectfully requests that you reply to this
> e-mail
> > and delete this message. AquaGeo, Ltd. accepts no responsibility for
> changes
> > made to this e-mail or any attachments after transmission from
> AquaGeo, Ltd.
> > Thank you.
> >
> > Thanks Pete,
> >
> > As workaround I manage to generate some input files: one for the
> > "power functions" and one for the "time variant ID". For the
> > generation of the file, I have temporary assigned the boundary
> > conditions as the time-constant and the I exported them as ASCII file
> > that I modified and imported again to simulate time-variant boundary
> > conditions.
> > However, I noticed that importing an external file using the command
> > "database" is quite tricky. Following the procedure described in this
> > forum:
> >
> > http://feflow.info/forum/index.php/topic,446.msg1332.html#msg1332
> <http://feflow.info/forum/index.php/topic,446.msg1332.html#msg1332>
> >
> > I used the commands: Assign - database - Import Time-varying IDs -
> > Head BC/Seepage - Automatic regionalization.
> >
> > But I had to use 'Inverse
> > Distance Weighting' with only one neighboring point as the
> > regionalization method for getting the exact numbers I wanted for each
> > node.
> >
> > In theory the command "interpolate" the data. To avoid the
> > interpolation I used "

Pete,
I have a terrible doubt now. If I define a power function (for a head
boundary condition for example)  file like the following one

!
!  t [d]      fvalue
!---------------------
730        334
1460      334

does it mean that the head boundary condition is off between 0 and
730? Running the model I noticed that is not like that but if I do not
want the boundary condition ON I have to use a fake head and a
constrain that is able to disable it between 0 and 730.

Giovanni


On Sun, Feb 8, 2009 at 12:59 PM, Pete Sinton <psinton@...> wrote:
> Hi Gio,
>
> Yes, that works.  I find it convoluted and cumbersome, so I resort to
> bypassing feflow's interface.  I know I will get what I want.
>
> Glad to hear you solved the problem
>
> Cheers
>
> --
>
> Pete Sinton
>
> Principal Hydrogeologist
>
> AquaGeo, Ltd.
>
> 11560 Penny Rd
>
> Conifer CO 80433
>
> Cell 720.841.5526
>
> Phone 303.838.7863
>
> psinton@...
>
> www.aquageo.us
>
> This e-mail together with any attachments is confidential and may be the
> subject of legal privilege. If you are not the intended recipient, you are
> not permitted to print, copy, disclose or use the content or attachments in
> any way.  AquaGeo, Ltd. respectfully requests that you reply to this e-mail
> and delete this message. AquaGeo, Ltd. accepts no responsibility for changes
> made to this e-mail or any attachments after transmission from AquaGeo, Ltd.
> Thank you.
>
> Thanks Pete,
>
> As workaround I manage to generate some input files: one for the
> "power functions" and one for the "time variant ID". For the
> generation of the file, I have temporary assigned the boundary
> conditions as the time-constant and the I exported them as ASCII file
> that I modified and imported again to simulate time-variant boundary
> conditions.
> However, I noticed that importing an external file using the command
> "database" is quite tricky. Following the procedure described in this
> forum:
>
> http://feflow.info/forum/index.php/topic,446.msg1332.html#msg1332
>
> I used the commands: Assign - database - Import Time-varying IDs -
> Head BC/Seepage - Automatic regionalization.
>
> But I had to use 'Inverse
> Distance Weighting' with only one neighboring point as the
> regionalization method for getting the exact numbers I wanted for each
> node.
>
> In theory the command "interpolate" the data. To avoid the
> interpolation I used "
>

Thanks Pete,

As workaround I manage to generate some input files: one for the
"power functions" and one for the "time variant ID". For the
generation of the file, I have temporary assigned the boundary
conditions as the time-constant and the I exported them as ASCII file
that I modified and imported again to simulate time-variant boundary
conditions.
However, I noticed that importing an external file using the command
"database" is quite tricky. Following the procedure described in this
forum:

http://feflow.info/forum/index.php/topic,446.msg1332.html#msg1332

I used the commands: Assign - database - Import Time-varying IDs -
Head BC/Seepage - Automatic regionalization.But I had to use 'Inverse
Distance Weighting' with only one neighboring point as the
regionalization method for getting the exact numbers I wanted for each
node.


In theory the command "interpolate" the data. To avoid the
interpolation I used "

On Sun, Feb 8, 2009 at 12:43 AM, Pete Sinton <psinton@...> wrote:
> Hi Gio,
>
> I see your point.  There's no way around it but you can create the node
> and power lists outside of feflow and edit them into an ascii fem. I've
> done a lot of this; let me know if I can help.
>
> *Pete*
>
>
> Giovanni Firmani wrote:
>>
>> Pete,
>>
>> assigning a pressure condition or a head condition for feflow is
>> exactly the same. Let assume (as in my case) I have to model a
>> seepage, I would use h=z and p=0. If the seepage boundary changes with
>> time I would need a different power function for each node (as there
>> is a different head for each node). But as p=0 is the same for each
>> node it would be easier to use only one power function for all the
>> nodes. This is the reason why I was wondering if it is possible to use
>> a power function for a pressure boundary condition
>>
>> Ciao
>> Gio
>>
>> On Sat, Feb 7, 2009 at 12:34 AM, Pete Sinton <psinton@...
>> <mailto:psinton%40aquageo.us>> wrote:
>> > Odd, but you are right. On my first attempt, it seemed to work, but when
>> > I looked at the node with the inspector, it indicated the boundary
>> > condition was a HEAD node, not pressure.
>> >
>> > It does not really matter though, because the help file indicates
>> > (consistent with physics) that feflow converts the pressure to total
>> > head anyway using equation h = p/(rho*g) + node_elevation. So if you
>> > input a pressure or a head, feflow ultimately operates on head. You can
>> > input a total head for the vadose zone and it will understand that the
>> > fixed head is above the water table if the head you input is smaller
>> > than the elevation of the node. Such nodes should probably only be set
>> > in a variable-saturation model, not confined or phreatic.
>> >
>> > *Pete Sinton*
>> >
>> > www.aquageo.us
>> >
>> >
>> > Giovanni Firmani wrote:
>> >>
>> >> I tried that
>> >>
>> >> When I use options->pressure instead of head I cannot define any
>> >> time-variant function. It seems that is not possible to assign a time
>> >> variant function for the presure :(
>> >>
>> >> Giovanni
>> >>
>> >> On Fri, Feb 6, 2009 at 3:56 AM, Pete Sinton <psinton@...
>> <mailto:psinton%40aquageo.us>
>> >> <mailto:psinton%40aquageo.us>> wrote:
>> >> > yes - it is done the same you would do with head, but select
>> pressure as
>> >> > the variable of choice. under the mesh inspector, set the light
>> >> > blue button to "options", then select "head (1st kind)" button.
>> Select
>> >> > pressure as the variable of choice.
>> >> >
>> >> > *Pete Sinton*
>> >> >
>> >> > www.aquageo.us
>> >> >
>> >> >
>> >> >
>> >> > Giovanni Firmani wrote:
>> >> >>
>> >> >> Is it possible to set up a time-varying function for the pressure
>> >> >> instead of the head when dealing with unsaturated problems?
>> >> >>
>> >> >> Regards
>> >> >>
>> >> >> Giovanni

Hi Gio,

I see your point.  There's no way around it but you can create the node
and power lists outside of feflow and edit them into an ascii fem. I've
done a lot of this; let me know if I can help.

*Pete*


Giovanni Firmani wrote:
>
> Pete,
>
> assigning a pressure condition or a head condition for feflow is
> exactly the same. Let assume (as in my case) I have to model a
> seepage, I would use h=z and p=0. If the seepage boundary changes with
> time I would need a different power function for each node (as there
> is a different head for each node). But as p=0 is the same for each
> node it would be easier to use only one power function for all the
> nodes. This is the reason why I was wondering if it is possible to use
> a power function for a pressure boundary condition
>
> Ciao
> Gio
>
> On Sat, Feb 7, 2009 at 12:34 AM, Pete Sinton <psinton@...
> <mailto:psinton%40aquageo.us>> wrote:
> > Odd, but you are right. On my first attempt, it seemed to work, but when
> > I looked at the node with the inspector, it indicated the boundary
> > condition was a HEAD node, not pressure.
> >
> > It does not really matter though, because the help file indicates
> > (consistent with physics) that feflow converts the pressure to total
> > head anyway using equation h = p/(rho*g) + node_elevation. So if you
> > input a pressure or a head, feflow ultimately operates on head. You can
> > input a total head for the vadose zone and it will understand that the
> > fixed head is above the water table if the head you input is smaller
> > than the elevation of the node. Such nodes should probably only be set
> > in a variable-saturation model, not confined or phreatic.
> >
> > *Pete Sinton*
> >
> > www.aquageo.us
> >
> >
> > Giovanni Firmani wrote:
> >>
> >> I tried that
> >>
> >> When I use options->pressure instead of head I cannot define any
> >> time-variant function. It seems that is not possible to assign a time
> >> variant function for the presure :(
> >>
> >> Giovanni
> >>
> >> On Fri, Feb 6, 2009 at 3:56 AM, Pete Sinton <psinton@...
> <mailto:psinton%40aquageo.us>
> >> <mailto:psinton%40aquageo.us>> wrote:
> >> > yes - it is done the same you would do with head, but select
> pressure as
> >> > the variable of choice. under the mesh inspector, set the light
> >> > blue button to "options", then select "head (1st kind)" button.
> Select
> >> > pressure as the variable of choice.
> >> >
> >> > *Pete Sinton*
> >> >
> >> > www.aquageo.us
> >> >
> >> >
> >> >
> >> > Giovanni Firmani wrote:
> >> >>
> >> >> Is it possible to set up a time-varying function for the pressure
> >> >> instead of the head when dealing with unsaturated problems?
> >> >>
> >> >> Regards
> >> >>
> >> >> Giovanni
>
>


[Non-text portions of this message have been removed]

Pete,

assigning a pressure condition or a head condition for feflow is
exactly the same. Let assume (as in my case) I have to model a
seepage, I would use h=z and p=0. If the seepage boundary changes with
time I would need a different power function for each node (as there
is a different head for each node). But as p=0 is the same for each
node it would be easier to use only one power function for all the
nodes. This is the reason why I was wondering if it is possible to use
a power function for a pressure boundary condition

Ciao
Gio


On Sat, Feb 7, 2009 at 12:34 AM, Pete Sinton <psinton@...> wrote:
> Odd, but you are right. On my first attempt, it seemed to work, but when
> I looked at the node with the inspector, it indicated the boundary
> condition was a HEAD node, not pressure.
>
> It does not really matter though, because the help file indicates
> (consistent with physics) that feflow converts the pressure to total
> head anyway using equation h = p/(rho*g) + node_elevation.  So if you
> input a pressure or a head, feflow ultimately operates on head.  You can
> input a total head for the vadose zone and it will understand that the
> fixed head is above the water table if the head you input is smaller
> than the elevation of the node.  Such nodes should probably only be set
> in a variable-saturation model, not confined or phreatic.
>
> *Pete Sinton*
>
> www.aquageo.us
>
>
> Giovanni Firmani wrote:
>>
>> I tried that
>>
>> When I use options->pressure instead of head I cannot define any
>> time-variant function. It seems that is not possible to assign a time
>> variant function for the presure :(
>>
>> Giovanni
>>
>> On Fri, Feb 6, 2009 at 3:56 AM, Pete Sinton <psinton@...
>> <mailto:psinton%40aquageo.us>> wrote:
>> > yes - it is done the same you would do with head, but select pressure as
>> > the variable of choice. under the mesh inspector, set the light
>> > blue button to "options", then select "head (1st kind)" button. Select
>> > pressure as the variable of choice.
>> >
>> > *Pete Sinton*
>> >
>> > www.aquageo.us
>> >
>> >
>> >
>> > Giovanni Firmani wrote:
>> >>
>> >> Is it possible to set up a time-varying function for the pressure
>> >> instead of the head when dealing with unsaturated problems?
>> >>
>> >> Regards
>> >>
>> >> Giovanni

Odd, but you are right. On my first attempt, it seemed to work, but when
I looked at the node with the inspector, it indicated the boundary
condition was a HEAD node, not pressure.

It does not really matter though, because the help file indicates
(consistent with physics) that feflow converts the pressure to total
head anyway using equation h = p/(rho*g) + node_elevation.  So if you
input a pressure or a head, feflow ultimately operates on head.  You can
input a total head for the vadose zone and it will understand that the
fixed head is above the water table if the head you input is smaller
than the elevation of the node.  Such nodes should probably only be set
in a variable-saturation model, not confined or phreatic.

*Pete Sinton*

www.aquageo.us


Giovanni Firmani wrote:
>
> I tried that
>
> When I use options->pressure instead of head I cannot define any
> time-variant function. It seems that is not possible to assign a time
> variant function for the presure :(
>
> Giovanni
>
> On Fri, Feb 6, 2009 at 3:56 AM, Pete Sinton <psinton@...
> <mailto:psinton%40aquageo.us>> wrote:
> > yes - it is done the same you would do with head, but select pressure as
> > the variable of choice. under the mesh inspector, set the light
> > blue button to "options", then select "head (1st kind)" button. Select
> > pressure as the variable of choice.
> >
> > *Pete Sinton*
> >
> > www.aquageo.us
> >
> >
> >
> > Giovanni Firmani wrote:
> >>
> >> Is it possible to set up a time-varying function for the pressure
> >> instead of the head when dealing with unsaturated problems?
> >>
> >> Regards
> >>
> >> Giovanni

I tried that

When I use options->pressure instead of head I cannot define any
time-variant function. It seems that is not possible to assign a time
variant function for the presure :(

Giovanni

On Fri, Feb 6, 2009 at 3:56 AM, Pete Sinton <psinton@...> wrote:
> yes - it is done the same you would do with head, but select pressure as
> the variable of choice.  under the mesh inspector, set the light
> blue button to "options", then select "head (1st kind)" button.  Select
> pressure as the variable of choice.
>
> *Pete Sinton*
>
> www.aquageo.us
>
>
>
> Giovanni Firmani wrote:
>>
>> Is it possible to set up a time-varying function for the pressure
>> instead of the head when dealing with unsaturated problems?
>>
>> Regards
>>
>> Giovanni

yes - it is done the same you would do with head, but select pressure as
the variable of choice.  under the mesh inspector, set the light
blue button to "options", then select "head (1st kind)" button.  Select
pressure as the variable of choice.

*Pete Sinton*

www.aquageo.us



Giovanni Firmani wrote:
>
> Is it possible to set up a time-varying function for the pressure
> instead of the head when dealing with unsaturated problems?
>
> Regards
>
> Giovanni

Is it possible to set up a time-varying function for the pressure
instead of the head when dealing with unsaturated problems?

Regards

Giovanni