[HuoYangze]

Hello, everyone,
I am currently conducting a simulation of the process of salt drainage and oxygen enhancement in dark tubes. I have divided it into three models. The following are my thoughts and issues:
In this process, I need to first establish the presence of salt ions in the soil area, and then set up a fresh water intake hole for irrigation. The fresh water will wash the salt down, with part of it entering the dark pipe through its holes and being discharged, while the rest seeps down to the underground pipe or even reaches the water table.
The second issue involves evaporation and soil capillary force. When the groundwater level is shallow, it rises as salt water. Part of this enters the dark pipe through its holes and is discharged, while some continues to rise above or even reach the surface.
For this process, I assume there is an air pump at one end of each dark tube. When there is no water in the tube, oxygen will be injected into it. Some of this oxygen will diffuse to the surface through its holes, while another portion will be discharged through its head.
I have encountered some problems with these three models that I do not know how to solve:
In model 1: 1) How can I simulate salinity in initial state soil (can polyphase Euler particle model be used)? 2) How can I track movement of salts in soil (or measure soil salinity before and after irrigation)?
In model 2: 1) How can I measure salt or brine content in soil after a period from underground pipe up to surface? 2) What material should be used to simulate saltwater?
In model 3: 1) How can I determine diffusion range of oxygen within a given time?
2) How can system be set up so that oxygen or air pressure within tube is relatively uniform? Is plugging pipe inlet or outlet necessary?
Should solvers for all three models be set as transient taking gravity into account?
I often encounter floating point exceptions during simulation calculations. What could be possible causes?
When creating dark tubes in Spaceclaim, should straight tubes first drawn for volume extraction followed by punching holes in tube wall and drawing hexahedron as surrounding soil part around dark tube section? Also how can numerous holes quickly and regularly made on tube wall? Is setting head end as inlet, tail end as outlet; upper/lower surfaces of soil as inlet/outlet; and holes as inlet/outlet correct for models 1-3 respectively?
As my language skills are still developing but time does not permit systematic learning before completing this simulation project,I am encountering many challenges.I would greatly appreciate any brief expert advice or assistance! Thank you very much!
HuoYangze