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Forum: CFX Yesterday, 18:27
Replies: 38
Views: 413
Posted By ghorrocks
As the rotation speed increases the boundary...

As the rotation speed increases the boundary layers will get thinner and the flow more turbulent (at least in the trailing section of the foil), and the turbulence transition point will move closer...
Forum: CFX Yesterday, 10:50
Replies: 38
Views: 413
Posted By keg504
RPM variation

I ran the simulations using the best grid I have, and I'm getting a systematic error of at least 15%, decreasing as the RPM gets lower. It's around 5% at 1606 RPM, but the next point at 2273 after is...
Forum: CFX May 4, 2024, 22:48
Replies: 1
Views: 62
Posted By ghorrocks
Have you tried using a frozen rotor interface?...

Have you tried using a frozen rotor interface? You can somewhat account for the frozen rotor's simplification of just modelling a single point in the rotation by sweeping it across a full pitch. Or...
Forum: CFX May 4, 2024, 07:20
Replies: 1
Views: 62
Posted By TurBoris
Frame Change Interface Location Between Rotating and Stationary Blades

Hi All,

Currently we have been conducting a high speed centrifugal compressor stage tests that has a pressure ratio more than 5 at its design point.

Our pre-test CFD results are off at some...
Forum: CFX May 4, 2024, 03:32
Replies: 1
Views: 53
Posted By ghorrocks
Have you done the CFX combustion tutorials? Make...

Have you done the CFX combustion tutorials? Make sure you have done any relevant tutorials so you know how to set it up.

But to answer your direct question - you can apply a heat source on a...
Forum: CFX May 3, 2024, 07:06
Replies: 1
Views: 53
Posted By bishwajitdgp
Post CEL expression for setting high temperature at a coordinate/ surface at time, t=10s

Hi

I want to simulate a combustion reaction in Ansys CFX. I am defined methane combustion (single-step) reaction.

I want to initialize a high temperature source in my geometry at time let say,...
Forum: CFX May 2, 2024, 22:43
Replies: 7
Views: 82
Posted By ghorrocks
On the constant density simulation, what are the...

On the constant density simulation, what are the maximum and minimum pressures the model predicts?

Please attach an output file from a variable density simulation.
Forum: CFX May 2, 2024, 22:09
Replies: 7
Views: 82
Posted By michaelhoo
It"s teady state. The result set as...

It"s teady state.

The result set as constant density material model is ok.

The max/min pressure is set as below and the pressure range is much wider than the real from the simulation of...
Forum: CFX May 2, 2024, 22:03
Replies: 7
Views: 82
Posted By michaelhoo
Yes, you are right, water hammer needs to modify...

Yes, you are right, water hammer needs to modify the density as a function of pressure.

The work set as constant density fluid is over, I wana discuss how the fluid slightly compressible will...
Forum: CFX May 2, 2024, 22:00
Replies: 7
Views: 82
Posted By ghorrocks
As the EOS is linear table generation is normally...

As the EOS is linear table generation is normally OK, you just need to make sure you have enough range to cover the highest and lowest pressure you will ever encounter + a tolerance for numerical...
Forum: CFX May 2, 2024, 21:53
Replies: 7
Views: 82
Posted By michaelhoo
Thank you for your reply! I am newer to the...

Thank you for your reply!

I am newer to the setting for the CFX software besides the basic setting.

The boundary is shown below:
Inlet: mass flow rate, outlet: static presure( 1atm)
Domain...
Forum: CFX May 2, 2024, 18:53
Replies: 7
Views: 82
Posted By ghorrocks
That is a bulk modulus EOS. It uses the bulk...

That is a bulk modulus EOS. It uses the bulk modulus of the material to slightly modify the density as a function of pressure. This is approach is typically used in things like water hammer.

Be...
Forum: CFX May 2, 2024, 12:13
Replies: 7
Views: 82
Posted By Opaque
Which equation of state is that one? What...

Which equation of state is that one?

What boundary conditions are you using? Once it is not compressible, pressure boundary conditions level matters. That is not the case for incompressible fluid...
Forum: CFX May 2, 2024, 11:39
Replies: 7
Views: 82
Posted By michaelhoo
Set Density with presssure,the result is not correct

Hi Everyone,

I am trying to simulate an incompressible fluid flow in a pump turbine.

I wanted to study the effect of micro-compression of water on hydraulic machinery. I added the density...
Forum: CFX May 1, 2024, 14:30
Replies: 38
Views: 413
Posted By keg504
I was doing it as described in (1), I suppose...

I was doing it as described in (1), I suppose that the way I did it is not the same as ghorrocks means? If that is the case, can you explain what section by section means here?
Forum: CFX May 1, 2024, 13:13
Replies: 38
Views: 413
Posted By Opaque
You cannot define the mesh independent study on a...

You cannot define the mesh independent study on a single component having it sharing a frame change interface with another component.

The accuracy of the interaction across the frame change...
Forum: CFX May 1, 2024, 08:48
Replies: 38
Views: 413
Posted By keg504
New result

I managed to run a new finer propeller mesh, and it seems that the results are getting worse. I don't have the computing resources to go even finer to investigate, especially since the results file...
Forum: CFX April 30, 2024, 05:13
Replies: 0
Views: 60
Posted By bishwajitdgp
Question BVM Combustion Modelling, Flamelet Library

I wanted to simulate deflagration model

I imported Methane Air FLL STP and NO PDF from reaction library.

I used k-omega as the turbulence model and BVM as the combustion model and while...
Forum: CFX April 30, 2024, 04:51
Replies: 2
Views: 3,651
Posted By bishwajitdgp
Question Flamelet Libary

I imported Methane Air FLL STP from the reaction library. While choosing BVM combustion model and selecting the reaction the following error being shown:

"Reaction 'Methane Air FLL STP': The...
Forum: CFX April 30, 2024, 04:00
Replies: 5
Views: 189
Posted By Gert-Jan
Yes. As long as they are ideal gasses, this is...

Yes. As long as they are ideal gasses, this is true. As an engineer, you can assume that this is the case at room temperature and atmospheric pressure.

As a scientist in chemical engineering, I...
Forum: CFX April 30, 2024, 02:53
Replies: 5
Views: 189
Posted By MNMK
Hello again:) I would like to be sure, when...

Hello again:)

I would like to be sure, when we talk about a range of Molar Fraction from 0 to 1 in Cfd-Post, It means from 0 to 100 percent of Volume fraction. Isnīt it?

wishes,
Forum: CFX April 30, 2024, 01:34
Replies: 51
Views: 16,875
Posted By Mohsin1
Exclamation Please update the link

Does anyone have rotor 37 geometry in stp format?
Forum: CFX April 29, 2024, 17:50
Replies: 2
Views: 1,762
Posted By ghorrocks
I do not do combustion modelling so will not be...

I do not do combustion modelling so will not be able to help you much, but I can recommend that the CFX tutorials are the best place to start when you are working out how to set up a model. Have you...
Forum: CFX April 29, 2024, 17:47
Replies: 38
Views: 413
Posted By ghorrocks
For an accurate CFD model, you need: 1) An...

For an accurate CFD model, you need:
1) An accurate mathematical model of the physics
2) An accurate numerical solution of the mathematical model.

A mesh sensitivity study only checks (2). If...
Forum: CFX April 29, 2024, 16:39
Replies: 38
Views: 413
Posted By keg504
Grid study

I've been running the grid study, and it was going pretty well when refining the air mesh. However, when I'm refining the propeller mesh, the thrust drops by ~3 N. I've only done 1 refinement (the...
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