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Porous media, Darcy law

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Old   March 29, 2021, 16:44
Default Porous media, Darcy law
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mrzarei
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Hi
I want to use porous media (darcy law) in reef3d, like kamath 2015 paper with application in OWC wave energy converter.
But unfortunately I do not know how and where I should apply it.
I would be so thankful if anyone can help me.
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Old   April 1, 2021, 07:13
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Porous media can be invoked by using B 240. In general though, the VRANS option is the more consistent way to calculate flow through porous media. VRANS can be used with options B 260 to B 310. See here for more details: https://reef3d.files.wordpress.com/2...cej_porous.pdf
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Old   April 1, 2021, 16:16
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Quote:
Originally Posted by valgrinda View Post
Porous media can be invoked by using B 240. In general though, the VRANS option is the more consistent way to calculate flow through porous media. VRANS can be used with options B 260 to B 310. See here for more details: https://reef3d.files.wordpress.com/2...cej_porous.pdf
Thank you so much,

I want to validate kamath paper in 2015 about oscillating water column, But unfortunately I have some problems.

In definition of porous media, I defined it at the orifice along with the parameters in the following command. but I have a problem with velocity, velocities exceeding the critical value.
I would be so thankful if you could help me with the definition of porous media location.

B 240 * double Darcy porous media as rectangular box: C;D;xstar t;xend;ystar t;yend;zstar t;zend
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Old   April 5, 2021, 12:43
Default equation of D in darcy porous media
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I want to use Reef3D, Please only refer me to the equation that used for "D" in darcy porous media, B 240.

Unfotunately I can't find it's equation in Reef3D codes.
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Old   April 6, 2021, 17:51
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For the OWC, you only use "C" from B240, "D" is zero. The background can be found here: https://reef3d.files.wordpress.com/2..._ijme-2015.pdf - have a look at equations 14 and 15. The other parameters describe the volume where the porous media is active.

In addition to B 240, also use B 241 1. This way, the porous media only impacts the vertical velocity component.
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Old   April 6, 2021, 17:57
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The implementation can be found in iowave_velsource.cpp.
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Old   April 6, 2021, 18:44
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Thanks a lot

I read both of kamath papers about OWC. He used C as a linear parameter of darcy law, but I want to use D as a nonlinear parameter for validation of an experiment that I read in another paper.

However, if you remember the formula that includes D parameter, please send it to me.

Regards
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Old   April 7, 2021, 07:36
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The complete formula is implemented for B 240, including the non-linear part:

Code:
porousterm = p->B240_D[n]*a->visc(i,j,k)*a->u(i,j,k) 
       + 0.5*p->B240_C[n]*a->u(i,j,k)*fabs(a->u(i,j,k));
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Old   November 18, 2022, 13:35
Default Error while simulating OWC device using CFD (Ref: Kamath et al., 2015)
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Hi,

I am trying to run a CFD case (OWC with porous media as a turbine) to familiarize myself with the simulations. But unfortunately, there seems to be some error. Can anyone have a look?

A file containing the code and STL file is attached.


Is it because of my STL file?

When I applied porous media on the solid surface of the OWC, the simulation ran well without any errors, but I was not getting airflow through the orifice when I visualized the VTU file in paravew, and the results are also not matching with the published literature. (Do I need to provide porous media on a solid surface or on an orifice?)

I also ran a code by providing a porous media on the orifice, but simulations popped up an error during the reef3d run saying EMERGENCY STOP -- velocities exceeding critical value N 61.

Any help on this matter is appreciated.

Thanks
Attached Files
File Type: zip OWC.zip (67.5 KB, 1 views)
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Old   November 19, 2022, 01:41
Default porous media in Reef3d
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Hi

In reef3D, two parameters of C & D were defined oppositely.
you should write C instead of D and D instead of C.
I checked it and got good results.



Quote:
Originally Posted by Varada View Post
Hi,

I am trying to run a CFD case (OWC with porous media as a turbine) to familiarize myself with the simulations. But unfortunately, there seems to be some error. Can anyone have a look?

A file containing the code and STL file is attached.


Is it because of my STL file?

When I applied porous media on the solid surface of the OWC, the simulation ran well without any errors, but I was not getting airflow through the orifice when I visualized the VTU file in paravew, and the results are also not matching with the published literature. (Do I need to provide porous media on a solid surface or on an orifice?)

I also ran a code by providing a porous media on the orifice, but simulations popped up an error during the reef3d run saying EMERGENCY STOP -- velocities exceeding critical value N 61.

Any help on this matter is appreciated.

Thanks
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Old   January 18, 2023, 09:04
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I'm having trouble figuring out the permeability coefficient mentioned in the publication by Arun Kamath et al (2015). As you can see from the attached image, they have provided the P and q values, and we are aware of the water's viscosity, but what about the A and L values? How did they arrive at 1/Kp=500000000?

Kamath.JPG

Reference: Kamath, Arun, Bihs, Hans and Arntsen, Řivind A. “Numerical investigations of the hydrodynamics of an oscillating water column device.” Ocean Engineering Vol. 102
(2015): pp. 40–50.
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