I have 2D reservoir model, where the cohesive crack is predefined inside the reservoir. The crack element is COH2D4P, with 0 kg/m3 density, because the crack has no fluid in it initially (it is void!). That’s why, in defining density for the stuff inside the crack, I only defined density for the pore fluid entering the cohesive crack.

*Density, dependencies=1, PORE FLUID

1000., , 0.

1050., , 0.05

Step 1 is *GEOSTATIC step. It runs fine!

Step 2 is the *CFLOW step, and here, I activate the gravitational force on fluid when fluid enters the fracture. The code is provided below where I activate the *GRAV force!

**

** STEP: Step-2

**

*Step, name=Step-2, nlgeom=YES, inc=7000, unsymm=YES

*Soils, consolidation, end=PERIOD, utol=6.5e+07, creep=none

1e-05, 150., 1e-11, 3.,

**

** LOADS

**

** Name: Load-1 Type: Concentrated pore fluid

*Cflow, amplitude=Amp-1

INLET_Nodes, , -0.005

** Name: Load-3 Type: Gravity

*Dload

Part-1-1.Coh_crack, GRAV, 9.805, 0., 0., -1.

But, I don’t think the *GRAV is working, because, more fluid should eventually settle down at the bottom of the fracture, not top. But that is not happening (as shown in the attached picture!). How do I get fluid to go downwards in the fracture? What am I doing wrong?

Please and thank you!