Use of grid coordinates in reaction sandbox

[Bisesh Joshi]

Hi all,

I'm trying to specify reactions for particular zones, and I want to use grid coordinates as shown below instead of material IDs. Is it possible to do so? 

Please let me know if anybody has any idea?

Thank you!

Best regards,

Bisesh

REGION upper

  COORDINATES

    0.d0 0.d0 2.7d0 

    1.d0 13.0d0 3.6d0 

  /

END

REGION middle

  COORDINATES

    0.d0 0.d0 1.2d0 

    1.d0 13.0d0 2.7d0

  /

END

REGION lower

  COORDINATES

    0.d0 0.d0 0.d0 

    1.d0 13.d0 1.2d0 

  /

END

--

Bisesh Joshi

PhD student

Water Science and Policy

Graduate College

University of Delaware

901-297-6761

[Hammond, Glenn E]

What is the reaction?

Glenn

From: pflotra...@googlegroups.com <pflotra...@googlegroups.com> on behalf of Bisesh Joshi <bjo...@udel.edu>
Date: Thursday, May 28, 2026 at 10:20 AM
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Subject: [pflotran-users: 8788] Use of grid coordinates in reaction sandbox

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[Bisesh Joshi]

Hi Glenn,

Thanks for the prompt response.

I'm trying to use a localized CN ratio-based SOM fermentation without depleting the volume fraction.

I want them to be similar to mineral reactions, but making them dependent on soil moisture and O2 inhibition.

These are reactions:

upper: REACTION 1.0 SOM_U + 0.5 H2O -> 0.5 DOM1 + 5.0 Ac- + 0.389 NH4+ 1.0 DOM2

middle: REACTION 1.0 SOM02 + 0.5 H2O -> 0.5 DOM1 + 5.0 Ac- + 0.441 NH4+ +1.0 DOM2

lower: REACTION 1.0 SOM_B + 0.5 H2O -> 0.5 DOM1 + 5.0 Ac- + 0.328 NH4+ +1.0 DOM2

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[Hammond, Glenn E]

Because reaction sandboxes do not recognize their spatial location, you need a parameter to serve as a reference. The simplest approach is to add a mineral reaction with a rate constant of zero, ensuring there is no change in mineral volume fraction, and then use the mineral volume fraction as your toggling parameter. You can assign different mineral volume fractions to each zone by setting initial conditions with distinct transport conditions/constraints. Does this explanation make sense?

Glenn

From: pflotra...@googlegroups.com <pflotra...@googlegroups.com> on behalf of Bisesh Joshi <bjo...@udel.edu>

Date: Thursday, May 28, 2026 at 11:00 AM
To: pflotra...@googlegroups.com <pflotra...@googlegroups.com>
Subject: Re: [pflotran-users: 8790] Use of grid coordinates in reaction sandbox

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