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
It is surprising that some spam messages are being circulated in the
group for past few days, though the group is moderated. I am trying to
look into the problem.
Peter,
I am not sure about oscillation. However, coarse discretization,
especially in the vertical, definitely causes numerical dispersion
in FEFLOW - at times, involving large errors.
Cheers,
Shlomo Orr.
----- Original Message -----
From: peter.schaetzl
To: feflow@...
Sent: Wednesday, November 26, 2008 1:47 AM
Subject: [feflow] Re: too much dispersion within an unsaturated flow and mass
transport model
Monica,
A too coarse discretization would typically lead to oscillations
rather than high numerical dispersion. So please check whether your
dispersivity values are realistic and whether you have turned on an
upwind method (in Temporal&Control data). Upwind methods stabilize the
solution on too coarse meshes, but depending on the method used a high
amount of artificial dispersion might be added.
Hope this helps
Peter
FEFLOW Support Team
I forgot something in my last post:
For open-loop systems, you often would like to link the injection
temperature to the abstraction temperature by applying a constant or
time-varying temperature differential. As this is not possible in the
standard user interface of FEFLOW, DHI-WASY provides a module for the
FEFLOW programming interface IFM for this, called SimpleOpenLoop. If
you need this, just email to the FEFLOW support (support@...).
Peter
Monica,
A too coarse discretization would typically lead to oscillations
rather than high numerical dispersion. So please check whether your
dispersivity values are realistic and whether you have turned on an
upwind method (in Temporal&Control data). Upwind methods stabilize the
solution on too coarse meshes, but depending on the method used a high
amount of artificial dispersion might be added.
Hope this helps
Peter
FEFLOW Support Team
Monica,
Among other things, FEFLOW (like some other models) suffers from
a large numerical dispersion. The simplest solution is to subdivide the
domain into many smaller ones (in your case, many layers).
Good luck,
Shlomo Orr.
----- Original Message -----
From: mirunache
To: feflow@...
Sent: Tuesday, November 25, 2008 5:59 AM
Subject: [feflow] too much dispersion within an unsaturated flow and mass
transport model
Gretings!
I am looking for advice regarding the model I have built in FEFLOW-
flow and mass transport in transient state, for an unsaturated
model.
The model is based on conceptual hydrostratigraphy, field data and
parameters as taken from referenced literature. However, for some
reason, I have the feeling that I get too much dispersion through the
model domain.
If anybody could give me some advice regarding this issue, I can
provide more detailed information.
Many thanks,
Monica
Gretings!
I am looking for advice regarding the model I have built in FEFLOW-
flow and mass transport in transient state, for an unsaturated
model.
The model is based on conceptual hydrostratigraphy, field data and
parameters as taken from referenced literature. However, for some
reason, I have the feeling that I get too much dispersion through the
model domain.
If anybody could give me some advice regarding this issue, I can
provide more detailed information.
Many thanks,
Monica
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