Hello everyone,

I am learning OGS6; I have a few queries and difficulties.

**1. Wrong Result from seepage simulation.**

I am simulating seepage (Rainfall seepage) with the existing regional groundwater table. I have generated Initial Condition (equilibrated regional groundwater table) by running gravity steps for a 100 years time period. Now, I am implementing the Rainfall seepage by mass flux through the top by specifying a Neumann boundary condition. I have applied the rainfall intensity of 420mm for 16 hours (7.292 x 10^3 kg/m2/sec).

But I am getting some high negative pressure pockets larger than the initial condition. As you can see in the following figure; the curve inside the blue circle is unwanted and the expected curve is the green line shown in the same figure.

What do you think causes this problem?? My professor told me time-stepping could be the culprit. I have used delt-t equal to 1 and 0.5 seconds, but still; I am getting a similar result.

**2. Related to VanGenuchten Saturation Curve**

The source code Documentation says that saturation is computed from the capillary pressure as follows:

I have plotted this graph with excel and I got this (pore water pressure shown in the following graph are negative suction pressure).

But when I plot the result obtained from OGS with the same parameter I got this.

Is this a bug or something I did wrong so I got this result?

Thank you for your support,

Regards,

Laxman Kafle

Input Files:2_RainfallSim.zip (4.3 MB)