GENERAL mode diffusion conditional question

[David Fukuyama]

I am curious about a conditional in the GeneralFlux subroutine that computes liquid and gas diffusion. On lines 1524 and 1946, there is the following conditional:

if (sqrt(sat_up*sat_dn) > eps) then

As far as I can tell, this conditional just checks that the two adjacent cells have a non-zero value (or slightly above zero). Is there a reason why this is done rather than just checking that sat_up > eps and sat_dn > eps?

Thanks,
David

[Hammond, Glenn E]

David,

 

I believe that “if (sqrt(sat_up*sat_dn) > eps) then” was the original code, but I wanted to have the option to allow for diffusion even when a phase does not exist. Therefore, I added the alternative “if (sat_up > eps .or. sat_dn > eps) then”. As you well know, “if (sqrt(sat_up*sat_dn) > eps) then” is similar to “if (sat_up > eps .and. sat_dn > eps) then”, but instead a geometric mean when it comes to the comparison to epsilon.

 

Glenn

 

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Subject: [pflotran-dev: 6226] GENERAL mode diffusion conditional question

 

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[Fukuyama, David Erik]

Thanks Glenn. Are there any special cases that the geometric mean catches that the other conditional would not?

 

From: 'Hammond, Glenn E' via pflotran-dev <pflotr...@googlegroups.com>
Date: Thursday, January 4, 2024 at 3:54 PM
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Subject: [EXTERNAL] RE: [pflotran-dev: 6226] GENERAL mode diffusion conditional question

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