darcy2D

2D Pump Test Darcy and Non-Darcy flow in Liquid Water and Gas

The use of Darcy’s law in subsurface porous flow models is nearly universal. However, there are important applications where Darcy’s law is not valid. Flow in fractures and flow near pumping or extraction wells are applications where Non-Darcy flow models are often required.
The code uses a fully implicit non-Darcy implementation with a control volume finite volume code (or control volume finite difference code) with a minimum of coding that allows for general non-darcy models.

Using the data from Zeng and Grigg (2006), these tests were designed to confirm the validity of the implementation. Both gas and liquid water pumping were examined in a 2D problem intended to approximate a pump test. Tests included here are Liquid Darcy, Liquid non-Darcy, Gas Darcy, and Gas non-Darcy.

Figure 1. Solution domain and liquid pressure comparisons for each value of beta model. Contour lines starting at lower left corner are MPa 2.8, 2.0, 1.0, and .5 furthest away from corner. Click on image for full view.

Black contour is Darcy with ndar OFF, and is equal to ndar set to beta 1.d6

Red contour is non-darcy with ndar beta set to 1.d9

Blue contour is non-darcy with ndar beta set to 1.d10

More images are in test directory FEHM/fehmpytests/darcy2D/_information/contour_darcy_m9_m6

Example macro ndar

The macro ndar is used to set non-darcy flow. The keyword off can be used to skip the macro and flow will be Darcy as usual.

In this example, 1 441 1 is the node number start,stop,stride. 1.0d9 is the flow model which can be 1.d10, 1.d06, 1.0d9, and Beta default 1.d-15. Note for this test, 1.d06 is similar to the Darcy result, and 1.0d9 is slightly different (red lines in Figure 1).

ndar
1 441 1 1.0d9

end ndar

or
ndar OFF (keyword **OFF** is used to skip a macro)

Example macro cont with vtk

The vtk option is available through the macro cont. In this example, vtk contour files are written at Time 0.0 and Time 50.0 rootname.00001_sca_node.vtk and rootname.00002_sca_node.vtk, each with contour data for Liquid Pressure (MPa) and Saturation. The pressure contour images were created using Time 0002 vtk files.

cont
vtk     5000    1.00000e+19

Reference

Document by George and Dolan pending.

Test Directory: FEHM/fehmpytests/darcy2D

Documents and Image Directory: FEHM/fehmpytests/darcy2D/_information