Learning Forum

[Timothée Herbeau]

Hello ! 

I am modeling multicomponent particles (ideally in steady state simulation) and hesitate between the trap boundary condition or wall film model. What I found appealing in the wall film model is the possibility to model particles splashing and then evaporating/moving forward... 

I think using the trap boundary condition is better in my case (especially as I want to do steady simulation) but I am concerned as I don't know how are multicomponent particles treated. According to the theory guide droplet material is transformed into gas instantly which is not what I would want as my particles are composed of water and other chemical species. 

Do you have any advice/ information on how are multicomponent particles treated ? 

 

Thank you so much !

Tim

 

 

 

 

 

[Rob]

It should evaporate as per the single component droplet. 

[Timothée Herbeau]

Thanks for the answer, so it does evaporate instantly...

 I have just read on an ansys guide (23.4. Setting Boundary Conditions for the Discrete Phase (ansys.com)) that "The particle no longer participates in heat transfer." So I am a little confused: When the particle arrives on the wall, both liquid and solid materials are passed into the vapor phase and then the remaining solid part is still going to be modeled by DPM or what happens exactly ? 

Thanks again !

 

[Rob]

What solid? Multicomponent is a droplet. If you have a particle I think it will dump the heat into the domain and the mass is removed - I've not checked. 

[Timothée Herbeau]

Maybe I misunderstood the guides but I thought you could add solid and liquid material to the multicomponent particle, isn't it the case ? (And in that case, what model should I use to model a flow of droplet in which there is a solid suspension ? additionnaly what option can model those particles sticking to the walls they are projected onto -keeping in mind that the wall film does not suit my will to do steady simulation-)

Thank you so much for your help, 

Have a good day

 

 

[Rob]

OK, I think you want the wet particles that are used in the combustion models. They're designed so you can boil/evaporate off the volatiles to leave a char which is then burnt. In your case you want to lose the volatile but retain the solid. 

For the wall contact, there isn't a model to then build up a mass of material. However, the accretion model will give you an idea of what hits where. 

 

But..... 

If you explain what phenomena you're trying to model (pictures are good) there may be alternatives. I need to be a little careful about my answers there as I'm not permitted to give "engineering advice" need to limit answers to public domain information but you may want to be looking at a slightly different modelling approach.