Learning Forum

[Jana.Greshnova]

Hello everyone,
I'm working with Ansys CFX 2025 R1 (student version) on an Euler-Euler multiphase simulation with a dispersed solid phase (0.5 mm particles, 40% volume solid fraction, brine as the continuous phase). The morphology is set to Dispersed Solid.

According to Ansys documentation, the dynamic viscosity of solids in this model is required but supposedly not used in the simulation. However, I tested several values (from 1e-5 to 0.1 Pa·s), and they have a clear and consistent influence on the pressure drop. You can see the effect below: 

Solids Dynamic Viscosity [Pa·s]	Total Pressure Loss [Pa]
0.00001	543
0.0001	562
0.001	611
0.01	784
0.046	1459
0.1	1783

This contradicts the expected behavior and the guidance in this article which says the value is required but ignored (https://innovationspace.ansys.com/knowledge/forums/topic/specifying-viscosity-for-a-dispersed-solid-phase-in-a-multiphase-flow-simulation/#:~:text=conductivity%2C%20etc,is%20specified%20as%20%E2%80%9CDispersed%20Fluid%E2%80%9D).

Can someone from the community or Ansys clarify:

• Why the dispersed solid viscosity affects the result?

• Whether this is a known bug or undocumented feature?

Thanks in advance for your help!
Jana

[V.P]

Hi 

You might find this link useful: Specifying viscosity for a dispersed solid phase in a multiphase flow simulation | Ansys Knowledge

[Jana.Greshnova]

 

Hi,

thanks, but this is exactly the article that my results completely contradict.

When creating a solid material, I did exactly as described here, but unfortunately I found that dynamic viscosity directly affects pressure loss (although according to this article it shouldn’t).

That's why the question is whether there were any changes in R1 2025 hier?

Or in general the use of a two-fluid flow with 40% solids for pressure loss calculation is not recommended and should be considered for this purpose Fluent?

Euler-Euler multiphase simulation. Dispersed solid. Inhomogen. Solid 40%. Brine 60%. 

Does anyone have any successful experience running this type of simulation?

Thanks in advance!

Jana