[yje1994]

Hi all,

I am trying to simulate a macro-scale air filter to trap particles in the porous zone (the porous zone acts as the air filter media).

Basically, I have a 2D rectangular geometry which is separated into three zone: inlet zone, porous zone and outlet zone. The particles come in steady-state from inlet and will be trapped in the porous zone. I assume all particles trapped in porous zone. Therefore, it should be no particles going into outlet zone.

I set injection type as "group", inert particle type. For boundary conditions, I have set "reflect" for inlet, "trap" for porous zone, "escape" for outlet zone.

However, what I have obtained is that all the particles come from inlet and escape to the outlet. I could not get any particles trapped in the porous zone.

Appreciate if anyone can assist on this situation.

Thank you very much.

Have a nice day and stay safe.

[vinerm]

Do you have porous zone as a cell zone or a boundary zone (porous jump)? If it is a cell zone, then there is no option to select trap for a cell zone. Furthermore, if you are already specifying that all the particles are captured, then what is the objective of simulating particles?

[yje1994]

Hi Vinerm,

I have a porous zone in cell zone conditions with defined viscous and inertial resistance. The porous zone is now representing a clean filter. With particles deposited, the pressure drop across the porous zone will increase. I wish to simulate the particles deposited at the filter area which set as porous zone, and at the same time affecting the pressure drop across it.

There is no option to trap the particles under cell zone conditions. Sorry, it was my understanding before this.

Is it the correct direction if the BC for inlet and outlet to be set as "reflect" and "escape". What I obtained with this settings is that all particles escaped to the outlet.

Thank you.

[vinerm]

Even if the particles are trapped by the porous zone, you will not observe any pressure increase. This is not how the models work in Fluent. This has to be done by the user. Pressure drop in a porous zone is only due to the resistance coefficients. If those are not changed, there will not be any pressure drop change across the zone. What you want to do needs to be done using UDF. Other option is to assume that particle deposition is homogeneous and then define an equation for resistance coefficients. In that case, you do not need to model any DPM but you will have to somehow determine the equation for resistance coefficients as a function of deposition rate.

[yje1994]

Hi Vinerm,

How about the particle deposition in porous filter? The particle deposition will be used to update permeability of porous zone (with UDF) and find the pressure drop. The process will be repeated until one desired pressure drop value.

[vinerm]

Yes, that is what you need to do. But it is not the porosity that you need to change rather the resistance coefficients. Porosity has no effect on the pressure drop or flow.