Learning Forum

[Achini]

Hello!nI'm trying to simulate the diffusion of polystyrene nanoparticles in a microchannel filled with water.npolystyrene nanoparticle in a water medium is introduced at the inlet of the channel.nNanoparticles travel through the channel via diffusion and I'm trying to simulate their motion using Ansys fluent.nI tried to use the species transfer model with inlet diffusion enabled, and I noticed backflowoccurring at the outlet of the channel. I defined the channel outlet as outflow but still there was backflow at the outlet.nI have attached snaps of the species transfer model settings and the resulting contour of polystyrene mole fraction along the channel.nCan someone tell me how to avoid backflow in the channel?nAlso, is there a better model to use for this simulation?nThank you!nnn

[Rob]

There's a flag in pressure outlet to prevent back flow. If the inlet velocity is zero chances are the backflow is numerical, ie the velocity will be +/- a very small value as the solver converges each time step. n

[Achini]

Hello sir!nThank you for your reply.nI couldn't find the option you mentioned. nCould you please tell me more about that? I have attached a snap of my pressure outlet settings.nThank you so much!nnn

[Rob]

nn

[Rob]

Which solver version are you using? n

[Achini]

Dear sir,nThank you for your reply.nI'm using Ansys workbench version 18.1. nI guess that option is not available in the version I'm using.

[Rob]

It's not, you need to update to a more recent build. R18 is 5 years old now. n

[Achini]

I installed Ansys workbench 2021 R1 and could eliminate reverse flow using that version.nThank you very much for your support sir!n