Alex Costall PhD Student

Thankyou! :D

G'day,

What do I need to set in order to allow mass-concentration to expand past the mesh limit?

Example;

In the picture below, the mass-concentration boundary node is clearly prohibiting the 'normal' movement of the seawater.

The node is currently set to a mass-concentration of 200 mg/L. The plume is about 20000 mg/L.

I'm sure this is related to the min/max mass-flow constraints, but I can't work out the right parameters :(

[img width=140 height=200]https://i.imgur.com/XApIeEB.png[/img]

Glad to hear from you!

It's a 2D planar model, with the simplest case of anisotropy (Isotropic?) in the problem settings, and just modifying the 'Anisotropy of Conductivity' value.

@Bjorn, any sage words for me? :P

An accidental google led to some suggestions of FEFLOW's ability to implement an adaptively refining mesh, yet I can't see the option in current versions!

Is it still there, or has it been removed since it's original implementation?

From the 7.1 help menu, it looks like you can use the empirical van Genuchten method as well as a few others!

http://www.feflow.info/html/help71/feflow/mainpage.htm#rhtocid=7.1.1.1.0_1&t=08_ProblemSettings%2FFlow%2Fflow_description.html%23

I'd like to know this process too - If you work it out, please let us know here!

I've managed to confuse myself regarding anisotropy settings.

In most cases I've seen, anisotropy is the ratio of the maximum to minimum.
e.g. setting it to '10' would net 10 times greater parameter in that direction.

However, in FEFlow, anisotropy of conductivity is defined as K_min/K_max

So, setting this to 10, such as the case before, would actually [i]reduce [/i]the flow in that direction - but, if K_min is 10-times greater than K_max, that doesn't make sense conceptually.

I'd like to set the flow to be 10 times greater in the primary direction than the orthogonal direction, do I need to set K to 10 or to 0.1!?!

Fantastic.

My thanks for both of your responses!

In the online help manual, we are given the following definition;

[quote]The application of a mass-concentration boundary condition can be limited by a minimum and/or maximum mass flow set as a constraint. If the flow at the node exceeds a set maximum, the concentration boundary condition is converted into a well condition with the value of the maximum mass-flow constraint. If the mass-flow falls below a specified minimum mass-flow, a well condition with the minimum value is applied.[/quote]

What is meant by a 'well condition'?


And, in the example seawater interface, why are these constraints placed on the seaward boundary?