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Topics - anner.paldor

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1
FEFLOW / Mass concentration BC constraint for seepage nodes
« on: July 07, 2020, 08:32:05 pm »
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.

2
FEFLOW / Exporting to Tecplot
« on: February 13, 2020, 12:30:20 am »
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.

3
Plug-in/Script Development / Exporting to Tecplot
« on: January 17, 2020, 05:13:32 pm »
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.

4
FEFLOW / Thermal expansion coefficient assigned to density ratio
« on: July 15, 2018, 10:54:50 am »
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.

5
FEFLOW / Buoyancy term in the rate budget
« on: October 02, 2017, 11:09:38 am »
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.

6
FEFLOW / Buoyancy term in the rate budget
« on: October 02, 2017, 10:29:14 am »
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.

7
FEFLOW / exporting vx and vy
« on: February 15, 2017, 12:49:15 pm »
Hello,
I am modeling a 2D aquifer, and I always record the results in full mode (DAC file). When I want to export the results of some measure (say head, or darcy flux) I simply go to the desired time-step in the DAC file, right-click the component in the view-components window, and then export. The thing is, when I export the Darcy flux results, it exports it as a scalar, with only the magnitude, whereas I am interested in the vector output with the 2 components (vx and vy). I know I can set observation points on the nodes I am interested in and then save the results in a reduced mode (DAR file) and then I can get vx and vy, but it seems weird to me that this is impossible to do with a DAC file.

Has anyone else encountered this problem? Any suggestions?

Many thanks in advance,
Anner.

8
FEFLOW / vx vy export
« on: February 29, 2016, 11:22:34 am »
Hello,
I am trying to get a simple table with four entries: coordinates and darcy velocity. x,y,vx,vy.
Exporting a .dar file crashes the software for some reason (7.0 version) and the .dac is a complete mess in excel. I've saved it in ASCII format, then successfully imported it to excel with commas, tabs and spaces as delimiters.   
I get half a million rows for a domain with ~85000 nodes and it is impossible to figure out the rows that are the vx vy components corresponding to the rows that are the coordinates. This is aside from the fact that coordinates repeat themselves over 12 columns, which is very hard to sort, and hard to correlate to node numbers listed over 3 columns.

Is there a way to get this information easily?

Many thanks in advance,
Anner.

9
FEFLOW / streamline plot without selection markers
« on: February 23, 2016, 07:40:02 pm »
Hello,
I am trying to export an image from a dac. file with streamline traces plot, but the image contains the yellow dots marking the selected nodes at which the streamlines are seeded. I've tried "lock data view" and still when I clear the selection the streamlines disappear. I've also tried leaving the selection and only switching to element selection mode, but it has the same effect as clearing selection.

Ideas, anyone?

Many thanks in advance,
Anner.

10
Suggestions / Darcy flux arrows by component
« on: February 18, 2016, 07:12:48 pm »
Hello,
I am working on a vertical 2D domain, modeling flow towards the sea. What I would like to be able to do is to color the arrows of darcy flux according to their magnitude, but with two different sets of colors according to the sign of their X component. I.e., arrows flowing towards the sea (lets say negative X component) are in shades of red while arrows with positive X velocities are in shades of blue.

Additionally, the possibilities regarding the representation of darcy arrows are too limited. For example, if my domain is too large (>10 km), than the arrows cannot be seen in a large perspective because darcy velocities are a few meters per day. Increasing the relative size of the arrows to the maximum (10) did not help. When I tried exporting the data to plot it myself, it turns out that FEFLOW exports only the magnitude and not the components. I suggest either to upgrade the plotting possibilities (in matlab, for example, the quiver plot can be manipulated in any exaggeration) or to enable exporting of the nodal darcy flux result by components.

Many thanks in advance,
Anner.

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