[Darshan C]

hello

As I am working on passing air as a working fluid inside a cylindrical chamber consisting of spherical pebbles(which have a porosity of 0.2) and the pebbles occupy 50% of the region in flow volume. What are the cell zone conditions needed to be given to the pebbles as well as the flow volume.

I have taken the pebbles as porous region.
Under steady state simulation I need to get a pressure drop of 5 Pa. But I am getting a drop of 0.2 Pa. (Note: It is a 2 dimensional model).

I have referred the model from (CFD Analysis for the Hydrodynamics and Heat
Transfer in Packed Pebble Bed)
by
N.S. Ghuge & D. Mandal

[Kushal Puri]

Originally Posted by Darshan C

hello

As I am working on passing air as a working fluid inside a cylindrical chamber consisting of spherical pebbles(which have a porosity of 0.2) and the pebbles occupy 50% of the region in flow volume. What are the cell zone conditions needed to be given to the pebbles as well as the flow volume.

I have taken the pebbles as porous region.
Under steady state simulation I need to get a pressure drop of 5 Pa. But I am getting a drop of 0.2 Pa. (Note: It is a 2 dimensional model).

I have referred the model from (CFD Analysis for the Hydrodynamics and Heat
Transfer in Packed Pebble Bed)
by
N.S. Ghuge & D. Mandal

You can define that as a porous jump condition and define the appropriate value of face permeability, porous medium thickness and pressure jump coefficient

[Darshan C]

Thanks for the quick reply sir.

In my case the pebbles are the porous medium so what should be the value for porous medium thickness.

[Kushal Puri]

Originally Posted by Darshan C

Thanks for the quick reply sir.

In my case the pebbles are the porous medium so what should be the value for porous medium thickness.

Can you show mesh image

[Darshan C]

The modelling and meshing was done using gambit

[Darshan C]

this is the full model meshing

[Darshan C]

this is the meshing between the pebbles and flow volume

[Kushal Puri]

Originally Posted by Darshan C

this is the meshing between the pebbles and flow volume

Actually no need to capture the pebels, you just make that a make mesh without pebels and define the porous coefficient. This is what porous modeling is.

[Darshan C]

Sir in the simulation that i am doing the pebbles are actually treated as a porous medium (darcy's law) whereas the flow volume surrounding it isn't (Navier Stokes equation).When modelling I have subtracted the pebbles from the flow volume, hence making it two separate volumes.I have no problem while meshing but when running the simulation under steady state laminar condition at a flow rate of 0.0016125 kg/s I had to obtain a pressure drop of 5 Mpa but my pressure drop is very small about 0.2.I had given pebble only as a porous medium and not the other volumes and also given the respective boundary conditions as stated below in the diagram.

Sir please tell me if I have gone wrong anywhere while simulating it.

[Darshan C]

This is the plot against which i want to validate my results

[Kushal Puri]

Originally Posted by Darshan C

This is the plot against which i want to validate my results

Can you send the case