## Fluids

Topics relate to Fluent, CFX, Turbogrid and more

#### Is there a way to calculate the grinding consumption through FLUENT

• hone zifu
Subscriber
• Rob
Ansys Employee

For powder milling? I suspect you'll want Ansys Rocky for that.

• hone zifu
Subscriber

My idea is to use fluent to calculate the amount of grinding of the object. I am currently doing CMP analysis and need to simulate the amount of grinding

• Rob
Ansys Employee

Please can you explain with pictures? I have no idea what the CMP analysis means, but may recognise it by a different name.

• hone zifu
Subscriber

Through fluent calculation like this, the grinding liquid enters the gap between the wafer and the pad for grinding. Is there a way to calculate the amount of grinding?

• Rob
Ansys Employee

If you can relate wall shear stress to grinding, yes. There's not a model in Fluent that'll do this directly.

• hone zifu
Subscriber

However, the model I set is to set water and air for vof. At present, only the flow field of water can be made.

• hone zifu
Subscriber
How should I set up according to your suggestion, thank you
• Rob
Ansys Employee

Linking shear to grinding? You need a correlation and you can then use a Custom Field Function (or UDF) to plot the value of the supplied correlation.

• hone zifu
Subscriber

If looking at shear alone, do I just need to set the shear force on the surface

• Rob
Ansys Employee

You'd be using not setting the value. It depends on what correlation you have and want to use. I can't help you with the what, that's for your literature review to figure out.

• hone zifu
Subscriber

Because the literature I read is mainly based on experiments, and I have not found anyone using fluent to calculate the amount of grinding.

• Rob
Ansys Employee

Fluent doesn't have a grinding model. Fluent can give you parameters that can be used in an experimentally derrived correlation to calculate a grinding rate. So you can do the experiment on a simple, safe system and employ Fluent for complicated, dangerous and expensive enviroments as part of the design process.

• hone zifu
Subscriber

Then if I set vof and DPM model to set water and particles for flow field analysis, can I know that the particles are in contact with the surface?

• Rob
Ansys Employee

You can check their position. There's also the erosion and accretion model(s), but they're designed for impact effects rather than grinding. However, if it's a high volume fraction of solids DPM isn't appropriate.

• hone zifu
Subscriber

Then I would like to ask how to set the proportion distribution of the liquid mixture concentration

• Rob
Ansys Employee

Of the DPM? Once they're in the system the particles will do where the flow takes them. Volume injection may be appropriate, but I don't think you want DPM for this. Is the liquid a high volume fraction slurry?

• hone zifu
Subscriber

Because my current idea is to flow into the pure liquid with a volume fraction of 1 first, then flow into the grinding dope after 30 seconds, and judge the distribution volume of the dope

• Rob
Ansys Employee

And would the grinding dope mix with the liquid? Is it a slurry?

• hone zifu
Subscriber

Yes, I'm going to do VOF for this part or component transfer is better

• Rob
Ansys Employee

If it mixes I'd potentially use species, but I'd also look at nonNewtonian viscosity for the slurry to avoid needing the solids. There's a fair bit of literature covering this - blood and sewage sludge being two fluids I've seen represented in this way.

• hone zifu
Subscriber

I don't intend to incorporate solid materials; instead, I plan to mix fluids with a density of one (water) with different densities.

• hone zifu
Subscriber
• hone zifu
Subscriber

I am conducting a Volume of Fluid (VOF) analysis using two immiscible liquids with different densities for rotation. However, in the volume fraction part, it doesn't seem like they are mixing together as intended.

• Rob
Ansys Employee

Immiscible and VOF, so the fluids shouldn't mix. If that's the phase volume fraction then the above looks sensible for that definition and model.

• hone zifu
Subscriber

If it is a hybrid VOF method, how should I modify the settings?

• Rob
Ansys Employee

You mean multi-fluid VOF? It's set from the Eulerian panel, but that's still two (or more) phases.

• hone zifu
Subscriber

mean? Also, I have another operational issue - I can't select the folder to save while creating animations."

• hone zifu
Subscriber

• Rob
Ansys Employee

Are you running in Workbench?

• hone zifu
Subscriber

YES

• Rob
Ansys Employee

WB sets all save locations etc to avoid files being lost.

• hone zifu
Subscriber

What I mean is that I cannot select the option to set the animation folder in Fluent.

• Rob
Ansys Employee

Because you're using Workbench. Fluent locks down the save options.