Learning Forum

[Sajjad Ghiasi]

How do I model water with mudd? I want to model a filter where muddy water enters and clear water comes out. Please help me.

[Rob]

What do you actually want to see in the model? Please review the courses in Learning before answering. 

[Sajjad Ghiasi]

goal is to pass a cloudy water through a porous medium and purify it and produce clear water. So that the concentration of pollution in the outlet can be seen

[Sajjad Ghiasi]

My goal is to pass a cloudy water through a porous medium and purify it and produce clear water. So that the concentration of pollution in the outlet can be seen and measured

[Rob]

OK, and which part of the porous media model do you plan to use for that?

[Sajjad Ghiasi]

 use porous zone in model,I also don’t know how to model turbid water?thanks.

[Sajjad Ghiasi]

 

I use porous zone in model,I also don’t know how to model turbid water?thanks

 

[Rob]

That depends. Do you need to worry about the particles, or can you just adjust the water density & viscosity? 

[Sajjad Ghiasi]

I want to make sure that the water coming out of the filter is clear and without contamination, does the density determine it?

[Rob]

No, it's a way of modelling a contaminated material without needing to try and track the phase. Species models can also be used, as can scalars (I've seen work on sedimentation tanks using that approach). You need to review the porous model in some detail to understand what it does, and also what mechanism you're using to clean the water. 

[Sajjad Ghiasi]

So what should I do?

[Sajjad Ghiasi]

So what should I do?.

[Rob]

Have you read the manuals and done the tutorials? If so, which of the various models best represents what you need to get from the model? Once you've decided, sketch out the domain so you can check what data you have, need and don't know. You can request the latter while building the geometry and mesh. 

[Sajjad Ghiasi]

I have no problem creating geometry and also meshing and I know perfectly well, my problem is creating the material needed for muddy water. I also studied the multiphase discussion, I think I should use the Mixture model.

[Rob]

How will you filter Mixture Model with porous media? For cloudy water, what is the relaxation time & settling velocity of the mud? What volume fraction have you got? What is the difference in the fluid properties between clean and muddy water?

Note, I am not permitted to give detailed advice, however, from experience I can ask questions or point you at public domain information to help you learn. 

[Sajjad Ghiasi]

Thank you for helping me. I am also a student who needs to model this project for my class. 

Does that mean I can't use the mixture model?? And since there is a pressurized environment inside my filter, I don't think the sedimentation speed is considered, and I use the Implicit Formulation.
 The difference between the properties of clean and polluted fluid is the presence of soil particles and any type of pollutant, which definitely has a higher density and higher viscosity.

[Rob]

Right, first off "I need it for my class" isn't a good starting point to build a CFD model. Instead work from the question you need to answer to determine what model is needed. 

Once you have that figured out, and have read up on the various models in Fluent you can work out what is needed. Note, if the mud content is high enough to mess with density & viscosity is a filter pack the best option? There's a reason the water industry uses a range of separation devices, both dynamic (cyclone type) and semi-static (sedimentation tanks) in addition to filters. 

[Sajjad Ghiasi]

My ultimate goal is to model the VPMF(Variable Pore Micro Filtration) system, but first I wanted to model a filter to see if this Is the goal achievable or not? 
Yes, it is true that there are many systems for this purification, but my goal is to study the (Variable Pore Micro Filtration) system. But I got confused in modeling!!

Sincerely.

 

[Rob]

We can model filters. But, you also need to work out scale: do you want to model the pores or the bulk system? Porous media is the most commonly used approach to capture the fluid flow, however there are no built in models to remove the filtered material: but do we need to? 

[Sajjad Ghiasi]

the vpmf system has threads made of pp or pe(polyethylene), where the impurities get stuck and the clear water comes out. My goal of modeling is this, can I equate it with a porous medium?
I don't want the filtered material to be removed. Modeling one cycle is enough for me. Thank you

https://www.youtube.com/watch?v=-kNlGynk2qo

[Rob]

OK, so that's a bit more difficult. Hence my questions. 

Modelling the bulk filter would use porous media and you'd just have to assume it worked but would be interested in pressure loss & velocity to improve system energy efficiency and avoid damaging the filter. 

Modelling separation by particles hitting fibres and forming a cake is much more complicated. If you can neglect the flow then Rocky (alone) is a good option. If you need include the flow it's messy and would need much more thinking: Rocky & Fluent would be coupled but there are size considerations to figure out.