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Why is Storage model in Darcy's Law time dependent?
Posted 6 gen 2016, 00:43 GMT-5 Fluid & Heat Version 5.1 4 Replies
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Dear all,
A simple square using Darcys Law. If I use the default "fluid and matrix properties" and make all the material properties as CONSTANTS, the result is static even if I use time dependent solver, and this can be explained from the governing equations. However, if I use "storage model" instead, make all properties CONSTANTS, including S, the result is now time dependent, which is contradictory to the governing equations (see attached figure). When density and porosity are constants, the time derivative term should be zero, which is not time dependent. Can anybody tell me why does this happen? Thanks a lot.
Regards,
Albert
A simple square using Darcys Law. If I use the default "fluid and matrix properties" and make all the material properties as CONSTANTS, the result is static even if I use time dependent solver, and this can be explained from the governing equations. However, if I use "storage model" instead, make all properties CONSTANTS, including S, the result is now time dependent, which is contradictory to the governing equations (see attached figure). When density and porosity are constants, the time derivative term should be zero, which is not time dependent. Can anybody tell me why does this happen? Thanks a lot.
Regards,
Albert
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4 Replies Last Post 14 gen 2016, 07:54 GMT-5
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Posted:
9 years ago
In the governing equations，the first eqation is the default "fluid and matrix properties", while the second one does represent the "storage model". The "storage model" is time dependent when S is not defined as zero.
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Posted:
9 years ago
In the governing equations，the first eqation is the default "fluid and matrix properties", while the second one does represent the "storage model". The "storage model" is time dependent when S is not defined as zero.
Thank you for your reply, Xu. I am still confused. Look at the left side of the second equation, if porosity and density is constant, which is the case in my model, should not the left side equals to zero?
Hope to hear from you soon. Thanks.
Regards,
Tianhang
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Posted:
9 years ago
The "storage model" use the right side of of the second equation instead of the left one. The parameter "S" repesents the storage coefficient (SI unit: 1/Pa).
The governing equation of the "storage model" takes the following form
this equation is independend of porosity.
The governing equation of the "storage model" takes the following form
this equation is independend of porosity.
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Posted:
9 years ago
Thank you very much for the explanation, Xu.