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Address consistency for terms in moisture PDE #224

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bwspenc opened this issue May 10, 2021 · 0 comments
Open

Address consistency for terms in moisture PDE #224

bwspenc opened this issue May 10, 2021 · 0 comments

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@bwspenc
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bwspenc commented May 10, 2021

Bug Description

The equation for moisture transport in concrete is expressed as:
image

In BlackBear, the solution variable is H (relative humidity). It's not immediately obvious how the terms are consistent. The term on the left (time derivative) and the term on the far right (dehydration) appear to be in terms of W (moisture content) rather than H. However, multiple authors (e.g. Wang and Xi, 2017) write the equation this way. If the correct units are used in the moisture diffusivity coefficients (D_h and D_{ht}), this can be an acceptable way to express this, but we need to make sure that we are actually using the correct units in the models we currently have, and document them accordingly.

Steps to Reproduce

This inherently affects any model using moisture transport.

Impact

At a minimum, the current documentation needs to be improved to clarify the units used in the moisture transport model and coefficients. This needs further investigation, and if there is an inconsistency in the models, we may need to adjust one or more of the terms in the differential equation accordingly.

bwspenc added a commit to bwspenc/blackbear that referenced this issue May 10, 2021
…daholab#224

This does two things:
1) Makes the time dependent term be in terms of RH rather than W
2) Removes the dehydration kernel because it's not clear how to cast
   that in terms of RH rather than W
bwspenc added a commit to bwspenc/blackbear that referenced this issue May 11, 2021
…daholab#224

This does two things:
1) Makes the time dependent term be in terms of RH rather than W
2) Removes the dehydration kernel because it's not clear how to cast
   that in terms of RH rather than W. We will add this back in later
   when it is needed, and make sure that is done correctly.
bwspenc added a commit to bwspenc/blackbear that referenced this issue May 11, 2021
bwspenc added a commit to bwspenc/blackbear that referenced this issue May 11, 2021
…daholab#224

This does two things:
1) Makes the time dependent term be in terms of RH rather than W
2) Removes the dehydration kernel because it's not clear how to cast
   that in terms of RH rather than W. We will add this back in later
   when it is needed, and make sure that is done correctly.
bwspenc added a commit to bwspenc/blackbear that referenced this issue May 11, 2021
bwspenc added a commit to bwspenc/blackbear that referenced this issue May 11, 2021
…daholab#224

This does two things:
1) Makes the time dependent term be in terms of RH rather than W
2) Removes the dehydration kernel because it's not clear how to cast
   that in terms of RH rather than W. We will add this back in later
   when it is needed, and make sure that is done correctly.
bwspenc added a commit to bwspenc/blackbear that referenced this issue May 11, 2021
@bwspenc bwspenc changed the title Inconsistent variables for terms in moisture PDE Address consistency for terms in moisture PDE May 12, 2021
bwspenc added a commit to bwspenc/blackbear that referenced this issue May 12, 2021
bwspenc added a commit to bwspenc/blackbear that referenced this issue May 13, 2021
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