Flow parallel to porous media

HannesVV · June 27, 2013, 07:31

Hello everyone,

I am new in this forum and I have got some questions regarding porous media in CFX.
I am working on research with perforated plates in CFX using a porous domain. You can see the geometry for the simulation in the link below. The air is flowing through a ringchannel. On the ringchannel is a small pipe mounted. The pipe is closed and is only opened and directly connected to the ringchannel. So the small tube is acting like a Helmholtz resonator. The opening are causing vortices of the flow. My task is to minimize the vortex formation with a perforated plate. The plate is perforated in the direction of the small tube.The porous domain representing the plate is highlighted in the picture of the link.

My questions are now:
1. Is it possible to taking acount of the direction of the perforation of the plate? I was triying this by:
- adding a directional loss model with a local coordinate system
- the streamwise direction tends in the direction of the small tube
- I set the streamwise permeability to a large and the loss coefficient to a small value
- the transverse permeability and loss coefficient vice versa

The problem is, that the presssure drop over the opening in the direction of the ringchannel is greater with the porous media using these settings, instead of becoming smaller.

2. The directional loss model is only working, when the flow is going trough the porous domain and not flowing parallel to it, is this right?
3. Has anyone of you done something comparabel? I can only find research papers about flow through a porous medium and not parallel to it.

I would really appreciate your help!
Best regards HannesVV

Here you can see the geometry of the case:
https://www.evernote.com/shard/s27/s...8157051c1cdf6c

Benfa · June 29, 2013, 08:28

Hi,

you need to know the pressure loss coefficients for your plate, ans the porosity! If you set everything correctly the pressure drop will be fine. For a first step set the transverse multiplier to 1000 or higher. this assumes that you have ideal directed flow after the plate. if the pressure drop still does not fit. your input is not ok

June 27, 2013, 07:31	Flow parallel to porous media	#1
HannesVV New Member Join Date: Nov 2012 Posts: 2 Rep Power: 0	Hello everyone, I am new in this forum and I have got some questions regarding porous media in CFX. I am working on research with perforated plates in CFX using a porous domain. You can see the geometry for the simulation in the link below. The air is flowing through a ringchannel. On the ringchannel is a small pipe mounted. The pipe is closed and is only opened and directly connected to the ringchannel. So the small tube is acting like a Helmholtz resonator. The opening are causing vortices of the flow. My task is to minimize the vortex formation with a perforated plate. The plate is perforated in the direction of the small tube.The porous domain representing the plate is highlighted in the picture of the link. My questions are now: 1. Is it possible to taking acount of the direction of the perforation of the plate? I was triying this by: - adding a directional loss model with a local coordinate system - the streamwise direction tends in the direction of the small tube - I set the streamwise permeability to a large and the loss coefficient to a small value - the transverse permeability and loss coefficient vice versa The problem is, that the presssure drop over the opening in the direction of the ringchannel is greater with the porous media using these settings, instead of becoming smaller. 2. The directional loss model is only working, when the flow is going trough the porous domain and not flowing parallel to it, is this right? 3. Has anyone of you done something comparabel? I can only find research papers about flow through a porous medium and not parallel to it. I would really appreciate your help! Best regards HannesVV Here you can see the geometry of the case: https://www.evernote.com/shard/s27/s...8157051c1cdf6c

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June 29, 2013, 08:28		#2
Benfa Member Benny Join Date: Apr 2012 Posts: 40 Rep Power: 14	Hi, you need to know the pressure loss coefficients for your plate, ans the porosity! If you set everything correctly the pressure drop will be fine. For a first step set the transverse multiplier to 1000 or higher. this assumes that you have ideal directed flow after the plate. if the pressure drop still does not fit. your input is not ok