Menu

Discussion Forum

New Discussion
Filter

Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

Boundary Conditions: Pressure head vs. Pervious Layer

Posted Jun 12, 2014, 1:36 p.m. EDT Fluid & Heat, Porous Media Flow, Modeling Tools & Definitions, Parameters, Variables, & Functions Version 4.3a 2 Replies

Carolyne Bocovich
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

We are creating a 2D, steady state, Darcy model of a clayey embankment acting as a dam with a sand foundation. Upstream of the dam is at a higher water level then downstream, both are constant.

A conditional boundary condition is being used to define pressure head as zero above the water level along the embankment boundary. Below the water level ("load") the pressure head takes into account the y-coordinate (elevation) with respect to the water level. The code to describe this is: "0 + (load-y)*(load >= y)".

Using the pressure head boundary condition along the embankment forces the pressure head at the boundary to be zero. The Phreatic line is forced to the embankment surface because of this boundary condition. We would like the model to calculate the steady state phreatic line within the embankment.

What is the best way to define the boundary condition to allow the model to calculate the zero pressure head within the embankment?

Is the pervious layer boundary condition more applicable to this situation? How is the pervious layer boundary different from the pressure head boundary condition? How do I appropriately apply the conductance and how is Comsol using the conductance value in the model?
2 Replies Last Post Jun 3, 2015, 6:18 a.m. EDT
COMSOL Moderator

Hello Carolyne Bocovich

Your Discussion has gone 30 days without a reply. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help.

If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base.

Pin Shuai
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 10 years ago Mar 24, 2015, 3:45 p.m. EDT
Do you find any info on pervious layer? I also had the similar problem

Pin
Do you find any info on pervious layer? I also had the similar problem Pin
Alessia Amabile
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 10 years ago Jun 3, 2015, 6:18 a.m. EDT
I had a similar problem and found this paper extremely helpful:
web.stanford.edu/dept/cee/faculty/freyberg/ChuiFreyberg.pdf
I had a similar problem and found this paper extremely helpful: http://web.stanford.edu/dept/cee/faculty/freyberg/ChuiFreyberg.pdf

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.

Suggested Content