Hi,

I have two problems about UDS modeling. There are three options for UDS Flux Function: none, mass flow rate, and a user-defined function. In FLUENT User's Guide it is said that "mass flow rate" and "user-defined function" options are both used for mass flow rate calculation. Is there any advantage of the latter over the former? In my option the example of UDS flux in the UDF manual has the same function with "mass flow rate" option. If "mass flow rate" instead of "user-defined function" selected for flux function in my UDS, can flux term be calculated accurately?

Also this problem appears in UDS unsteady function, can the default option for unsteady function calculate the unsteady term accurately?

I'd appreciate your help. Thanks in advance.

[Maryam-A]

Hi
what option did you select finally?
I use UDS for adding nanoparticle concentration equation to investigate the Brownian and Thermophoresis, so I think I should use UDF_flux to make flux function of UDS by density of particle, but it divergence detected in momentum
maybe no need to use UDF-flux?
but when I select mass flow rate as convection term of UDS, it definitely uses density of nanofluid(function of volume fraction of particle and temperature) and I think it is wrong because no change is between using UDS and non UDS in velocity and temperature field.

I will be grateful if anybody help me