Negative and positive values in mass balance file

[navya anneldho]

Hi everyone,

I was looking at the mass balance file and noticed that in the “ymax Water Mass [kg/y]” column ('ymax' being a region I specified within my domain), some values are positive and some are negative. Just to confirm my understanding: in this context, positive values indicate flow into the domain, while negative values indicate flow out?

Similarly, I noticed some values being positive and some negative in the “ymax Water Mass [kg]” column as well. Could you clarify what the signs represent in this case?  

Thank you!

Sincerely,

Navya

[Hammond, Glenn E]

See my comments in red.

Glenn

From: pflotra...@googlegroups.com <pflotra...@googlegroups.com> on behalf of navya anneldho <navya...@gmail.com>
Date: Thursday, September 4, 2025 at 12:17 PM
To: pflotran-users <pflotra...@googlegroups.com>
Subject: [pflotran-users: 8553] Negative and positive values in mass balance file

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Hi everyone,

I was looking at the mass balance file and noticed that in the “ymax Water Mass [kg/y]” column ('ymax' being a region I specified within my domain), some values are positive and some are negative. Just to confirm my understanding: in this context, positive values indicate flow into the domain, while negative values indicate flow out?

Correct. Positive fluxes are into the domain and negative fluxes are out. Note that this is the instantaneous flux [mass/time].

Similarly, I noticed some values being positive and some negative in the “ymax Water Mass [kg]” column as well. Could you clarify what the signs represent in this case?  

Same concept, except this is the cumulative flux. You can imagine that the cumulative flux can go positive if the sum of the mass flowing into the domain (positive) is larger the sum of fluxes going out (negative). Cumulative flux is calculated by multiplying each instantaneous flux by the time step size over which it is applied. When you output such data, be sure to use "PERIODIC_OBSERVATION TIMESTEP 1”. To ensure the you output values for all timesteps.

Thank you!

Sincerely,

Navya

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