initial condition in EOS3 for volume elements with zero gas saturation

in a model I am working with, at initial condition all volume elements are fully saturated with water, and there is only one element which is fully saturated with air. I am using EOS3, and I set MOP(19)=0.

Now I want to assign these initial conditions. In PARAM.4, I need to put gas pressure in all grid blocks as an initial condition. I don´t know which value I have to put while gas saturation in these volume elements is zero.

Can anyone help me? 

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  • Under fully liquid saturated conditions, capillary pressure is zero, and thus the liquid pressure is equal to the gas pressure. So provide pressure, air mass fraction in the liquid phase, and temperature as the initial conditions.

  • Dear Stefan,


    Thanks for your reply, but I am wondering I didn´t explain the problem clearly. In my model, there are 2 phases(all blocks are fully saturated with water in liq. phase except one elemnt which is fully saturated with air in gas phase),so I set NPH = 2 MULTI. That means I am supposed to provide gas pressure, gas saturation (instead of air mass fraction in liq. phase) and temperature. -Even in this situation I should provide water pressure, gas saturation (which is zero or 10), and temperature an an initial condition(except for the elemnt which is fully saturated with air)?

    I would appreciate it if you could have a look at the attached Input and Mesh file.

  • Youhanna,

    There are some fundamental misunderstandings. You have to decide for each element whether it has a single phase (either all liquid or all gas) or two-phase conditions - that ill determine the primary variables (it has little or nothing to do with NPH). Please try to understand the primary variables table in Section 6.3; it should then become obvious that a primary variable of 10.0 is not a valid option. It appears that (at least initially) you only have single-phase points in your model (where gas saturation is NOT a primary variable).

    You may also want to consult some of the material in the Tips & Tricks section of the Forum, specifically http://esd.lbl.gov/files/research/projects/tough/support/initial-boundary-conditions.pdf


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