Learning Forum

[mreza65]

Hi there,
I was just wondering to ask you regarding interactions between particles and a continuous fluid.
According to the Theory guide of Ansys, One-Way coupling means consideration of the continuous fluid effects on particles, and Two-Way coupling is used for assessment of interactions between based fluid and particles and their effects on each other.
Now based on the addition of DEM option in the recent versions of Fluent, it means consideration of interactions between particles, and also between particles with boundary conditions. So, please let me know that it is still called Two-Way Coupling?

(particle or parcel is not important)
regards

[Amine Ben Hadj Ali]

4 way coupling.

[mreza65]

Thanks a lot. As a final question in this post, when we active some options in Physical Models tab in Discrete Phase Model such as Thermophoretic Force or DEM collision, FLuent considers the effects of their interactions on heat transfer? Or should we add UDF in this way?

[Amine Ben Hadj Ali]

DEM collisions: heat dissipation due to collision is not taken into account.

Regarding other models: indirectly as the trajectory is affected.

[mreza65]

Thanks for your help, Amine.

1- Could I ask you to give me a clue to write a UDF for heat dissipation in DEM collisions? Is there any example in UDF Guide to write and hook up?

2- Until now, I've found that FLuent cannot consider heat dissipation in 4way coupling (i.e. DEM) and I have to add UDF to take it into account. However, as you said: "other models may affect indirectly the trajectory".  For example, based on the Thermophoretic Force, particles in temperature gradient tend to migrate toward the cold side. I was wondering to know that in the Two-Way Coupling method, the heat dissipation caused due to interaction between particles (or parcels) and the based fluid is indirectly considered in the energy equation. Have I understood it right?

regards,

M.reza

 

[mreza65]

I've read the limitations when using the DEM collision model in Fluent User's Guide.

DEM particles do not transfer heat from particle to particle during contact. I just want to know how can take into account this heat transfer by UDF?

[Amine Ben Hadj Ali]

No sorry I cannot provide any Udf hints. It would be tough work so something for PhD or long master thesis get started from macro dpm collide.

[mreza65]

Thanks. Indeed, I am a PhD student and studying the possibility of this subject. As the last question, to reach this gold (consideration of heat transfer of DEM or other forces directly in energy equation), will I be able to do that by udf or I have to develop my own code?

[Amine Ben Hadj Ali]

Udf.

[mreza65]

I'm sorry, can you clarify it a bit further? Through which DEFINE Macros?

 

[Amine Ben Hadj Ali]

Scalar Updates and dpm sources terms to get started.