[Rohit Tripathy]

Hi ,
I am new to CFD . I am currently working on a project that involves study of the cavitation phenomenon in a marine propeller which would require the simulation to be performed using multiphase flow. I am using ANSYS Fluent 12.0.16. Could someone please guide me on how to perform a multiphase flow simulation in Fluent ? Any help would be highly appreciated.

[ghost82]

Hi your problem is not very simple; I'm performing some cavitation simulation on fixed object and here is what I can recommend to you:

- use the mixture model with cavitation model enabled; to use the full Singhal et al model, in newer version of fluent, you have to activate it from the command window, digiting yes when asking to use the Singhal et al model: solve/set/expert

- You can use rotating reference frame or sliding mesh: second one method is more expensive in terms of calculations

- Check your mesh to be an high quality mesh, possibly structured

- You could need to write some udf to adjust results: turbulent viscosity, compressiblity of liquid medium, custom cavitational model, etc.

- Start from simple case, without enabling cavitation, then once you reached a converged solution enable cavitation

- Use first first order discretization scheme, then try to switch to higher oders.

These are only preliminary advices, good luck my friend!

Daniele

[samir_cfd]

Hello Mr Daniel !!

Please I am simulating cavitation of 5 bladed marine propeller using Ansys Fluent,

I am new in simulating multiphase flow, and i need if it is possible steps to simulate cavitation using Fluent

Best regards

Samir

[ghost82]

I think you can read some tutorials about sliding meshes, mrf and cavitation.
search on google, there are some pdf tutorials to understand what you should do.

Daniele

[like.no.other]

This is an example of cavitation around a hydrofoil:

link
password: www.cfdiran.ir

[drsattar]

Hi for all
I am trying to simulate 5 MW offshore wind turbine (aerodynamics study only) using CFX to validate my results which were coming from another solver, under these conditions
· Full scale of 5 MW offshore wind turbine dimensions
· transient analysis
· Inlet velocity = 9 m/sec
· 3 blade rotor + hub (rotating domain) with angular velocity =1.08 rad/sec
· Nacelle + tower (stationary domain)
· Then, three interfaces have been defined between the stationary domain and the rotating domain due to changes in reference frames. In order to rotate the rotor in ANSYS.
· I create appropriate and suitable meshes for all the parts in ICEM and CFX is specifying domains, boundary conditions, type of analysis, interfaces, etc.

But I always I find this error

First side of interface |
| Domain Interface 1 |
| seems to contain a vertex at R=0 (Rmin/Rrange < GGI ETA TOLERANCE).|
| This is not supported with |
| PITCH CHANGE/Option = Automatic |
| Please use |
| PITCH CHANGE/Option = None |
| instead. |
+--------------------------------------------------------------------+
+--------------------------------------------------------------------+
| ********* WARNING ********* |
| Coordinate transformation of interface |
| Domain Interface 2 |
| into a radial interface resulted in some faces with a very small |
| axial extent. There are two possible reasons for this: |
| 1. The interface contains axial faces (normal to the axis). |
| If this is the case, please split the interface into two parts, |
| so that the purely axial sections could be transformed |
| properly. The transformation type (axial or radial) is chosen |
| automatically based on the largest interface extent. |
| 2. This message may be generated because of a tolerancing issue |
| when the mesh resolution in the axial direction is very |
| small (e.g. at the hub or shroud). If this is the case, you |
| may ignore this message. |
+--------------------------------------------------------------------+
+--------------------------------------------------------------------+
| ERROR #001100279 has occurred in subroutine ErrAction. |
| Message: |
| ****** FATAL ERROR ****** The orthographic view transformation fa- |
| iled on domain interface "Domain Interface 2". Failure may be du- |
| e to r=0 included in transformed cylindrical coordinates of an in- |
| terface with rotational relative motion. Another reason could be |
| that the interface contains faces that are parallel and others t- |
| hat are perpendicular to the rotation axis. |
+--------------------------------------------------------------------+


</SPAN>

When I selected (PITCH CHANGE/Option = Automatic ) which I thought is correct chose but the above error will appear
And when I selected (PITCH CHANGE/Option = None) the run continue and complete, everything is ok, but the values of torque is negative ???

[mkjadhav]

Hi Sattar,

I am doing flow analysis of radial turbine in CFX. I encountered same error as you mentioned above.
Whether you got solution for that?
Please reply as soon as possible.