Learning Forum

[Shubham Chaudhari]

I am simulating a Reactor model, in which a static bed of particles viz. carbon and ferrous mixed with composition of 0.5 volume fraction. 

Air entering the reactor model creating the swirling motion in the reactor which is taking particle with it at certain height, 

The aim of simulation is to find out the height of the particle moving in reactor and porosity of particles. 

I am using eulerian model with DDPM apporach in which i have to create static bed of particle without injection. 

My first question is: should I go with DDPM apporach to solve the model or eulerian apporach with more phases and patching the solid domain in whole mesh will take care of simulation?

Second question is: How to find out porosity of particle after the simulation. 

The static bed is of 2cm height in the domain of 15 cm. 

[Rob]

Are you expecting the bed to be entrained by the air? DDPM sounds a good fit, but the packing model isn't necessarily ideal for the static part; Eulerian granular is better for the two sections but you'd need to consider whether you need a particle size distribution as that requires additional phases or population balance models. Try both and see how they behave. Ansys Rocky coupled to Fluent is a good choice, but is lacking combustion models unless you fancy messing with the advanced parts. 

The particle volume fraction is a normal report from Fluent. If you mean the individual particle porosity following a reaction, that's rather more involved as there isn't a model for that: we assume (or calculate) a size and composition based on what's going on in the domain. 

[Shubham Chaudhari]

Hi Rob,

Thanks for the quick reply,

I am thinking of considering elurian model with granular apporach in which particle diameter will be given as input. 

But i am not sure that, two solid phase particle can be interacted through this model(Euler Granular). DDPM is good choice but it will take high computational cost for me. 

Also creating injection for static bed is quite difficult, hence i am looking forward to patch the solid domain in simulation. 

For your question, yes bed is entrained by the air. 

I have use Rocky DEM earlier in my previous corporate experience but i am not sure how to coupled with FLUENT (No Tutorials for one or two way coupling)

Further to the information, after completing the flow simulation, it require to perform phase change and chemical reactions in this problem, for which i am confused to which model will be better suited for me (DDPM or Euler Granular) to go forward. 

[Rob]

Coupling Rocky is pretty easy and is controlled from the Rocky side. It'll see capability upgrades etc over the coming versions, we can do a lot more using user coding. I'm one of the European Rocky specialists as part of my more general remit to cover the weird stuff (just don't ask me about modelling cars & aeroplanes). 

There's a volume injection in 2022 for DPM, use that, but remember to keep volume fraction low to avoid packing issues. With Eulerian (not DDPM) just patch in the solids at a bit less than the packing limit. 

Previous corporate experience? Depending on the licence maintenance if you're a commercial user you can contact us directly. We're limited by export rules on here so can only give limited support: the checks required for direct contact remove that limitation. 

[Shubham Chaudhari]

Hi Rob,

Great to heat that you are the man behind Rocky DEM, and i am not going to ask for building a Formula 1 car.

Group injection seems promising for this problem, Does group injection, limit the injection of particle to the boundary of domain which we will create explicitly in the fluid domain? Also, Does this zone need to be address as solid domain? 

With respect to euler granular model (Not DDPM), can we see track the particles in the fluid zone or it will be just representation of particles in the contours format?

Yes we are commercial use of ANSYS, but dont want to engage esteemed teams of ANSYS engineer before getting all the possible points for this problem. 

Also how we can install the Rocky DEM with FLUENT or workbench platform?

 

 

[Rob]

Volume injection is cell centre for every (most - look at the options) in the selected zone. It's for the fluid zones only, I have no idea what will happen if you inject particles into a solid: I also wonder if anyone thought to test it! 

With Eulerian Granular you'll see concentration contours. DDPM shows tracks (as it's using DPM formulations plus some extra bits). Ansys Rocky DEM shows particle positions (not tracks - it's transient) but models all contacts, so particle count becomes the limiter relative to compute. 

If you're using commercial licences by all means come on here, but please contact the local team. We can offer far more advice in private. 

Ansys Rocky can be downloaded from the Portal, and you'd then install once the Ansys software is ready. I tend to run Fluent from Rocky when I want coupled systems, and don't use Workbench. You will need a licence, so another reason to contact the local team.