## Omega Dual Porosity / aw Dual Permeability

A discussion forum for users of the new HYDRUS 2D/3D. HYDRUS is a software package for simulating water, heat and solute movement in two- and three-dimensional variably saturated media. Happy Posting!
Panag
Posts: 4
Joined: Thu Jun 22, 2017 9:12 am
Location: Denmark

### Omega Dual Porosity / aw Dual Permeability

Dear Jirka,

I am using the dual porosity model (water content m.transfer) and the dual permeability model. I have a question related to the omega (mass transfer coefficient) in dual porosity. The Omega in dual porosity (T^-1) is equal or very close with the aw (LT)^-1 ? Because I have made the calibration for the Omega in dual porosity, and now I want to use that value in dual permeability to estimate the a (half the fracture spacing) using the below equation:

aw = β * d^-2 * Ka * γ , where d is the half the fracture spacing

so, can I use the value of Omega from dual porosity in the above equation as aw?

As I have understood, I can use that, because the only difference is that for the dual porosity (water c. m. transfer), the omega is constant and so it is not depending from the pressure head, and that is why is 1/T. But for saturated conditions omega and aw in both models should be equal

Kind Regards

Jirka
Posts: 4762
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

### Re: Omega Dual Porosity / aw Dual Permeability

I’m currently traveling in China. I will start answering these questions next week when I get back to Riverside. J.

Jirka
Posts: 4762
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

### Re: Omega Dual Porosity / aw Dual Permeability

No. I do not think that they are the same. As you said, these two parameters even have the different units. Also, you should not have the mass transfer under saturated conditions (degrees of saturation would be equal to 1 in both domains). J.