TAGGED: #multiphase_models, diffusion, scalartransport, udf


April 24, 2024 at 10:44 amchuminhkhueBbp_participantHi, everybody.
I'm doing: particles transport is modeled by a convectiondiffusion equation in ansys fluent 2023R2.
 steadystate model. multiphase model: Eulerian.Primary phase material: Newtonian.second phase material: nonNewtonian.I am very confused when implementing the convectiondiffusion equation using UDF.I did it using 2 methods after read section 1.3. UserDefined Scalar (UDS) Transport Equations in Ansys Fluent Theory Guide.
method 1:define UDSI by DEFINE_ADJUST and diffusion coefficient by DEFINE_DIFFUSIVITY
Method 2: implement fully equation by DEFINE DIFFUSIVITY.
I don't know what is the most accurate way to describe the equation.I am looking forward help from experts and knowledgeable users
Thanks you so much!!! 
April 24, 2024 at 1:48 pmRobForum Moderator
What is diffusing where? Ie what are you trying to replicate as the second phase won't diffuse in the primary phase, it'll convect and be affected by turbulence.Â

April 24, 2024 at 11:38 pmchuminhkhueBbp_participant
Sorry for this omission,
it is a laminar model.
I model the transport of the particles using a convectiondiffusion equation due to the motion of the mixture, composed of the primary phase and the second phase.
Assume that the particles are influenced by the motion of both the primary phase and the secondary phase.
A mixture of domains contains particles.


April 25, 2024 at 10:49 amRobForum Moderator
Aren't the particles the second phase? If so, their motion is covered by the multiphase model.Â

April 25, 2024 at 10:59 amchuminhkhueBbp_participant
That's right. particles (platelets) defined by UDSI and move by multiple phases


April 25, 2024 at 12:51 pmRobForum Moderator
OK. Convection will be handled by the solver. Scalar diffusivity will be more difficult as phase boundary isn't recognised in the model and you may need to account for density.Â

April 26, 2024 at 9:13 am


April 26, 2024 at 10:42 amRobForum Moderator
Do the platelets really diffuse through both phases? If they're diffusing it's a species model, or scalar.Â

April 26, 2024 at 11:30 amchuminhkhueBbp_participant
Yes, I am describing it using a scalar model.I have tried the two methods above based on UserDefined Scalar (UDS) Transport Equations in Ansys Fluent Theory Guide. but I don't know if it matches the concept of ansys fluent.


 You must be logged in to reply to this topic.

376

187

167

156

140
Â© 2024 Copyright ANSYS, Inc. All rights reserved.