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Variable Ep in Richards Equation.

Posted Apr 7, 2017, 9:51 a.m. EDT Porous Media Flow 1 Reply

Ather Abbas
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I am trying to understand variably saturated flow example to implement Richards equation to model flow in unsaturaed zone. In the module of Richards Equation, there is a variable 'Ep' which has not been described in description of that problem, neither it has been given a value during implementation of model but it shows up twice in the module, once in main equation of Richards equation and once in storage model. What is this 'Ep' variable and what is its significance in Richards equation.
1 Reply Last Post May 29, 2017, 12:13 p.m. EDT
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Hello Ather Abbas

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Juan Pablo Aguilar Lopez
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Posted: 7 years ago May 29, 2017, 12:13 p.m. EDT
Hello Ather,

Ep (Epsilon p) stands for "Effective porosity" of the soil which determines the total storage of void volume in the soil. If you check the storage model tab in the Richard's equation model tab you can see that it is multiplied by the compressibility of the fluid in one term and its complement (equivalent to fraction of soil in the volume) is also multiplied by the compressibility of the matrix. while it is noted as Ep is is exactly the same as what they refer to as "Saturated liquid volume fraction" in the matrix properties which is noted as Thetha sub s. If you go to the help content of the Richards equation it is noted as a function of theta sub s instead of Ep.

Cheers

Hello Ather, Ep (Epsilon p) stands for "Effective porosity" of the soil which determines the total storage of void volume in the soil. If you check the storage model tab in the Richard's equation model tab you can see that it is multiplied by the compressibility of the fluid in one term and its complement (equivalent to fraction of soil in the volume) is also multiplied by the compressibility of the matrix. while it is noted as Ep is is exactly the same as what they refer to as "Saturated liquid volume fraction" in the matrix properties which is noted as Thetha sub s. If you go to the help content of the Richards equation it is noted as a function of theta sub s instead of Ep. Cheers

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