Vertical slice unsaturated model

Hi

I am a new to FEFLOW and am trying to build a vertical slice of a hill slope. As I was having problems with convergence and the rate budget, I have now build a smaller, simplified version of the model (attached). I am using the Richard's equation (variable substitution, but have tried all of them) and the modified van Genuchten. I have a constant head boundary on the right and a Neumann boundary at the top in order to simulate recharge, which I want to turn off and on. I have a couple of issues at the moment:

(1) I am using a constraint on the Neumann BC to limit head to the topographic surface. However, when recharge is 0, the constraint is still on and I have a constant head boundary, which I need to get rid of.

(2) My error_norm_flow is undefined. How do I switch it on?

Danke!

Sarah

[b](1) I am using a constraint on the Neumann BC to limit head to the topographic surface. However, when recharge is 0, the constraint is still on and I have a constant head boundary, which I need to get rid of.[/b]
You use a maximum head constraint on NeumannBC's. The constraint is active only in areas where the water table reaches the topography (right hand side). In contrast, the constraint is not active where the water table is below the topography (left hand side). From the technical point of view, FEFLOW produces the correct output. If you do not want to have the constraint active you need to change the value for the constraint.

[b](2) My error_norm_flow is undefined. How do I switch it on?[/b]
I agree the error norm must not be undefined. Instead, the distribution must be filled with the nodal errors. For me it seems to be a bug. I need to get the final confirmation. The bug will be fixed with the next Update.

In the meanwhile I provide two suggestions on how to improve the model. The capillary fringe as indicated by the saturation shows some artificial jumps. I suggest to refine the mesh. Moreover, I also suggest to switch to the direct equation solver PARDISO in the Problem Settings. The number of elements you (will) have in your 2D model should be easily handled by PARDISO.