Thanks for the link but it sends me to the Vol. V and when I google the vol. IV, nothing shows up. I tried to find ideal element size in the link you provided but it does not seem to be there. Probably because it is in the vol IV and the link sends me to Vil. V?<br>
I just want a basic definition about what there things are and if they are related with the diameter of the well and the size of the mesh elements around the well.
I cant find info about what is the virtual radius and the ideal element size. Can someone explain what these attributes are?
I want to input, into BC head-constant nodes a max. flow-rate constraint = 0 m3/d and a min. flow-rate = -5 m3/d. So I select the nodes where the constraints are to be applied and the I go to the Data Panel, and in the Hydraulic heads BC I open the menu and click on ad parameter,  I then click in min. flow-rate constraint and, as in your documentation files on this issue, I double click on the value in the editor toolbar. No change happens in the units (which should be by them m3/d) once we are applying a constraint to a constant head BC. If I click on the green checkmark, what happens is that the value in the editor toolbar enter as my BC and when I do the Inspection it comes as unconstrained. <br>
How, then can I enter constraints? Must I define on the Problem settings that the model is constrained?<br>
By the way, as soon as I click on the green checkmark, the option of the constraint I selected previously, simply disappears from the BC menu Add parameter. This means that if I try to apply it to an area of my river network and then go to a completely different area of the model, and select a new set of nodes, if I go to the Add parameter, that type of constraint is no longer available. How can I overcome this?
This large regional model is being simulated for natural conditions - meaning, no pumping wells active - and when I run it, it completely floods. And it floods a lot!  I suspected it could be my conductivity values, so I removed them and used the default FEFLOW values instead, just to check. Then I run the model and still floods, although not as crazily as before and not the whole model but around many of the BCs. I tried with conductivities Kx = Ky = Kz = 100 and the model still floods and in the same places.<br>
So my problem is not just the conductivities but something else as well. In this stage of the calibration I am using the head constant BCs for the river network. Recharge enters the model thorough In/Outflow on top/bottom.<br>
So then I returned to the default conductivity of FEFLOW and tried to simulate using sepage face constraints in the BCs where flooded areas occurred in their neighborhood. No change occurred. It still flooded.<br>
I the started to simulate through different definitions of the 1st slice (all the remaining 31 ones are defined as Dependent). It just <strong>didn't flood</strong> when I defined the 1st slice as Phreatic, constrained head on top of model domain. But in this case the Imbalance was on the same magnitude of Recharge (10^6 when the magnitude of the BCs was 10^8), so it is a too large imbalance. In all the other possible options <strong>it flooded and in the same areas, always </strong>(such areas are always neighboring the BCs). The exception is when 1st slice was defined as Free, constrained head on top of the model . In these cases it still floods but only on a few nodes. However the Imbalance if the 1st slice is Free is less than 1 m3/d, which is too low. So what is going on and what solutions might be implemented?<br>
I am not willing to define constrained heads on top so I thought that defining constraints would be a solution. However when I click the nodes to apply the constraint, once I just click them once the window on top of the screen to define this constraint does not show up with m3/d, as it should but remains with the head units. Is this because I just click once in the nodes of the BCs? If not, then how sould I do it to define the constraints?<br>
I have a large model with a large river network. The top of my model is defined by the DTM. I have a shapefile of the river network that I want to import as a Fluid-transfer into my model. How I do this in a way that the BCs will be assigned to the valleys of the DTM?<br>
I tried the method I use for the hydraulic properties, selecting the whole slice and it applied the BCs to all the nodes of the slice which is not what I want.<br>
I also want to apply constraints to those BCs, once FEFLOW floods large areas of the model, which is not correct. However, and once the river network is big, is defined by a large number of nodes with this BC type. So it is too time-consuming define the constraints node-by-node. How can I define constraints for the whole river network in a fast way?<br>
And just to be sure, the values of the Fluid-transfer BCs are the water height of the river, right? So if my river has 1 m of water, that is the value I should define in the BCs, correct?<br>
By the way, so far I am simulating this river network as head-constant BCs and when I check the imbalances by adding the BCs values and recharge (entered through In/outflow on top/bottom) in an Excel sheet and compare with the values shown in FEFLOW Rate Budget panel I get this: I f the 1st slices is defined as Phreatic, then the Imbalance in Excel match that of the Rate Budget panel. However if I define the 1st  slice as Free, the Imbalance in Excel and in the Rate Budget panel do not match and have a mismatch from 2 to 3 orders magnitude. Why is this so?
<span style="font-size:11pt"><span style="line-height:107%"><span style="font-family:"Calibri",sans-serif">I have a regional model that with the assumed K of the formations and the calculated recharge (even if divided by half) <b>floods with heads of 8 km above the model top</b> (= topographic surface), for most part of the model area.</span></span></span><br>
<span style="font-size:11pt"><span style="line-height:107%"><span style="font-family:"Calibri",sans-serif">So <b><u>I removed recharge</u></b> and put the model with the FEFLOW default K = 10 m/d in all the slices of the model (31 slices). But in spite of recharge (input through <u>In/Ourtflow on top/bottom</u> applied to slice 1) = 0 m3/d and Kxx = Kyy = Kzz = 10 m/d and the other flow parameters also as FEFLOW default, <b>the model still floods</b>, altough now head above topography values range from circa 1 to 10 m. <b>It is not in the whole model area as before but it floods around the boundary conditions</b>.</span></span></span><br>
<span style="font-size:11pt"><span style="line-height:107%"><span style="font-family:"Calibri",sans-serif">My boundary conditions are <u>hydraulic head = elevation</u>, are set in the 1st slice and represent the river network, once I have no data on river stages.</span></span></span><br>
<span style="font-size:11pt"><span style="line-height:107%"><span style="font-family:"Calibri",sans-serif">My initial head = 0 m in the whole model and the lowest Elevation value in the 1st slice is = 0.6 m. So my initial head is always below the topographic elevation of the model top.</span></span></span><br>
<span style="font-size:11pt"><span style="line-height:107%"><span style="font-family:"Calibri",sans-serif">The error tolerance is = 0.00005727</span></span></span><br>
<span style="font-size:11pt"><span style="line-height:107%"><span style="font-family:"Calibri",sans-serif">The model is defined as <u>Unconfined aquifer</u>, Slice 1 as Phreatic and the remaining ones as Dependent, <u>Storage change in phreatic top layer where water table exceeds the surface</u> as Extend storage of unconfined layer to the water table (once I assume there can be areas where flloding might occour, however not with the extension and location of the present floods in the model) and I set <u>Head limits for uncofined conditions</u> as Unconstrained on Top and Bottom of the model, once below my model area there are limestones which also are aquifers.</span></span></span><br>
<span style="font-size:11pt"><span style="line-height:107%"><span style="font-family:"Calibri",sans-serif">The rate budget has an imbalance of around 2550 m3/d and the BCs have outflows of circa 6.182x10<sup>6</sup> and inflows of circa 6.1824x10<sup>6</sup>.</span></span></span><br>
<span style="font-size:11pt"><span style="line-height:107%"><span style="font-family:"Calibri",sans-serif">I also made an attempt with <u>Head limits for uncofined conditions</u> as Constrained head on Top of model domain (and recharge = 0) but <b>the model sitll flooded around the boundary conditions</b>.</span></span></span><br>
<span style="font-size:11pt"><span style="line-height:107%"><span style="font-family:"Calibri",sans-serif">By the way, I also tried to change the K values, setting the whole model at Kx = Ky = Kz = 100 m/d and in another simulation at 1 m/d. The <b>flood occured in the same areas as when Kx = Ky = Kz = 10 m/d</b>, what changed where the values in the rate budget. Awhen there was K = 100 m/d these where 10 times larger that when K = 10 m/d and when K = 1 m/d where 10 times smaller as when K = 10 m/d.</span></span></span><br>
<span style="font-size:11pt"><span style="line-height:107%"><span style="font-family:"Calibri",sans-serif">I also tried to use Seepage face but the flloding problem remained.</span></span></span><br>
<span style="font-size:11pt"><span style="line-height:107%"><span style="font-family:"Calibri",sans-serif">All these simulations – except the initial one with the “real” K and recharge – were performed with recharge = 0.</span></span></span><br>
<span style="font-size:11pt"><span style="line-height:107%"><span style="font-family:"Calibri",sans-serif">From all this I suspect that there is too much water entering the model through the boundary conditions. So I tried to set up constraints. However when I select the nodes with the BCs I want to constrain, then click on Hydraulic head BC in the Data panel, and click on Add paramenter and choose for instance max. flow-rate constraint in the window</span></span></span><br>
<span style="font-size:11pt"><span style="line-height:107%"><span style="font-family:"Calibri",sans-serif"> there is no indication of a flow rate but only a head value that I can change. So I cannot define the flow rate. I’ve checked with the Inspection after entering a value in this above window and there is no constraint defined.</span></span></span><br>
<span style="font-size:11pt"><span style="line-height:107%"><span style="font-family:"Calibri",sans-serif">So, how can I define this flow rate?</span></span></span><br>
<span style="font-size:11pt"><span style="line-height:107%"><span style="font-family:"Calibri",sans-serif">And is it realy that my problem stems from the fact that there are no constraints in the BCs or is there something else?</span></span></span><br>
<span style="font-size:11pt"><span style="line-height:107%"><span style="font-family:"Calibri",sans-serif">One last question: when FEFLOW finds that the error is below the error tolerance and ends the simulation, this error below the errro tolerance is the average of errors in all the nodes between one simulation and the next one or is the highest error between simulations in at least one node of the model?</span></span></span><br>
My panel Data hás no option to define inactive cells. There shoukd be an option Activew/inactive cells but there isn't. How can I define inactive cells in this situation?
I have a regional model that is an expansion of a earlier one. There are slight changes in the node distribution of the mesh, once I had to add the new areas. I want to define boundary conditions in this new model using the boundary conditions of the former one. So I exported the BC in question (head constant along rivers) from the earlier model using the export Data and Current slice (where this BC was defined). I opened the exported file in a SIG and, as expected, it was a point shapefile with all the points along the rivers, as it should be. Aftewards I imported this file into the panel Maps and linked Z (the height of the terrain) to head constant BC, as in the former model. I mantained the default snap distance (2091,61 m). Then I went into the panel Data, selected head constant BC and when did the procedure to apply the BC along the nodes, I found that it did not defined the BC as it was in the shapefile – that is along the direction of the rivers – but applied it to all the nodes of the area I selected. The way I found to overcome this was to select node by node, for it to apply the BC in the correct nodes. Once this BC has to be applied to the whole river network, so theere is a lot of nodes, I would like to know how can I import the BC shapefile in a way that just the rightful nodes are defined, instead of all the nodes of the model. I have the same problem with the multilayer wells shapefile
I would like to know what is more important for an efficient performance of a model: eliminate all Delauney violations or equilateralise the triangles? Once I have to do this manualy I have no time to do both, so which should I choose?
By the way, is there a way to autmatically eliminate all Delauney violations? Smoothing the mesh helps but is far from elimminate all violations.
Hoping to ear from you, Emília Novo
I am running my model, and I got the message "PCG has a matrix with 13127th diagonal element <=0". The model seems run and seems to converge but does not calcularte the piezometric heads. I defined the conductivity, head-constant BCs, recharge on inflow/outflow on top/bottom as 300 mm/year and the remaining material properties I used the default values.
I send a file with some more info.
How can I overcome this and get the model calculating the heads?