Anner Paldor Student

Hello,
I am simulating seawater intrusion in a coastal aquifer with a portion of the model domain being the seafloor. For the seafloor nodes, I want to have a constant seawater head BC, and a conditional mass concentration BC, with zero-gradient for negative fluid flux (outflow) and C=Cmax otherwise. In other words, for the seafloor nodes I want seawater concentration if there is no seepage, but the BC turned off (or replaced by a zero-gradient BC) if there is seepage.
I wanted to use the mass concentration BC with a min mass-flow constrain of zero, which means that the BC is active only if seawater infiltrates (mass-flow > 0), but I'm not sure this does what I want. Does it?
Thanks in advance,
Anner.

Hello all,
Does anyone have a simple work around for exporting .dac in ASCII to tecplot? I remember there was once a way to do it with some pre-editing of the .dac file in notepad++, and making it .plt. but I don't really remember how to do it and I can recall that it was extremely cumbersome, so if anyone has a quick method that he is willing to share I'd be grateful.
Thanks!
Anner.

[quote author=CP link=topic=21705.msg28594#msg28594 date=1572877389]
Hello everyone

I'm simulating a saltwater intrusion on a simple model which is set to be bounded by a [b]hydraulic head BC by the western side and a saltwater head by the sea boundary (to the East)[/b]. As far as regards mass transport boundaries, I have set a [b]constant mass concentration BC by the sea boundary (35000 mg/l) and I am setting a saltwater inflow in the western boundary[/b], only in the last two model slices (as my saltwater intrusion should cross all my model in the last two slices). However, when  starting simulating the mass transport I can't avoid oscillations and negatives values in the concentrations at the edge of the intrusion. Moreover, even if I set a saltwater inflow only in the last two slices, salt spreads all over the system by the end of the simulations. The mesh was set up to maintain a Peclet number of less than 1 given the dispersivity and I have also ensured that it had <5% obtuse triangles.  I've tried different upwinding techniques, but none of those remove the problem entirely either.  Also, I have tried a more gradual introduction of saltwater by varying the western concentration, but as soon as any saltwater enters the system negative values appear...

Any suggestion that can help to avoid these problems?
Thanks!!!
[/quote]

Hi CP,
I'm not sure what exactly the problem might be, but from the two sentences that I have bolded in your message, it seems that you're assigning a salt mass concentration on [u]both sides[/u] (why do you have saltwater inflow in the western boundary if your sea is to the east?). If that indeed is the case, then salt spreading across your entire domain is the expected result.

Hello,
I have read some posts here related to exporting simulations results to Tecplot, but some are too old and probably irrelevant for current versions.
Does anyone have a method for visualizing (and processing) FEFLOW results with Tecplot? I remember in one project of my Ph.D. doing this very primitively - recording full simulation results (.dac) in ASCII format, and then editing the .dac file with notepad++ to make it readable by Tecplot. There are 2 problems with this: (1) it is extremely cumbersome and there's got to be an easier way, and (2) I don't quite remember how I did that...
If anyone has some insights or has developed any tools and is willing to share - I'd be very grateful.
Many thanks in advance!
Anner.

Hi Bjorn,
Sorry for the late response.
I am using update 11.

Anner.

Hi all,
Just wanted to share something that is probably very important to some of you.
I ran some simulations with both heat and mass transport calculations, and then wanted to compare the results to isothermal simulations. What I did was to simply tske the file of the previous simulation and save it as fem, and then in the problem class settings I unchecked the "heat transfer" option. Everything seemed ok - all the options that are irrelevant for simulations with no heat calculations (e.g. temperature BC etc.) disappeared, as expected. But when I ran the simulation the salt-fresh water interface took a very weird shape - nearly vertical. After a few weeks of deep confusion I found out that the density ratio had been assigned the value that pertained to the thermal expansion, after I turned off the heat calculations. So instead of modeling saltwater with density of 1025 kg/cum (density ratio 0.025) the saltwater in my model was actually nearly as dense as the freshwater (the density ratio was 0.0001 - which is the value of the thermal expansion).

Just wanted to give a heads up to those of you who might encounter this. Hope I can help others avoid the confusion I suffered...

Cheers,
Anner.

Hello,
I am running a 2D vertical, transient model of flow and mass transport aiming to simulate the Henry problem under different conditions. I run the simulation until the system reaches pseudo steady state, in which the salinity in nodes on the fresh-salt water interface is constant with time, and the water flux in and out of the model is equal. The thing is, when I examine the model in terms of rate budget, I get huge volumes of water entering and leaving the system through the no-flow boundaries at the top and bottom of the model, as terms of distributed source/sink. Additionally, the y-component of the darcy flux isn't zero on those nodes where the boundary is set to no-flow. Both "source/sink" and "in/out transfer rate" in the material properties in the data panel are set to zero. The stranger thing is that even on nodes completely within the domain, far from the boundary, there are non-zero calculated values of rate budget. These nodes are on the fresh-salt interface, where density gradients are most significant. It is obviously related somehow to buoyancy term, but I can't figure out how is it possible that the system loses water from nodes away from the boundary or from nodes that are on a no-flow boundary.


Any help would be greatly appreciated.
Anner.

Hello,
I am running a 2D vertical, transient model of flow and mass transport aiming to simulate the Henry problem under different conditions. I run the simulation until the system reaches pseudo steady state, in which the salinity in nodes on the fresh-salt water interface is constant with time, and the water flux in and out of the model is equal. The thing is, when I examine the model in terms of rate budget, I get huge volumes of water entering and leaving the system through the no-flow boundaries at the top and bottom of the model, as terms of distributed source/sink. Additionally, the y-component of the darcy flux isn't zero on those nodes where the boundary is set to no-flow. Both "source/sink" and "in/out transfer rate" in the material properties in the data panel are set to zero. The stranger thing is that even on nodes completely within the domain, far from the boundary, there are non-zero calculated values of rate budget. These nodes are on the fresh-salt interface, where density gradients are most significant. It is obviously related somehow to buoyancy term, but I can't figure out how is it possible that the system loses water from nodes away from the boundary or from nodes that are on a no-flow boundary.

Any help would be greatly appreciated.
Anner.

Hi Bjorn,
Sounds good. I've been meaning to jump into the Python water for some time now... This is probably the time. I'll be in touch with you.

Many many thanks again.

Many thanks, Bjorn. Unfortunately, I am unfamiliar with Python coding (to my shame...).
I guess I'll stick to the old (and quite cumbersome) DAR export.