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Pump Cavitation Analysis in ANSYS CFX (Part II)

Cavitation

This blog is the continuation of the series of blogs on the pump cavitation analysis in ANSYS CFX and automation of this process by using CEL (CFX Expression Language) and Perl script. The previous blog can be found under the following link;

Pump Cavitation Analysis in ANSYS CFX (Part I)

In the recent blog we are introducing to the second step in the pump cavitation analysis in ANSYS CFX, i.e. the cavitation model will be turned on and the solution will be initialized by the results from the step 1 (please refer to section for details).

 

Step 2: High Pressure Simulation of Pump with Cavitation Model turned on

 

1.2.12 Saving Case File with new name:

 

Open the “CFX_CAV_Off.cfx” file from the previous run with the Cavitation model turned off.

Go to: File > Save Case As… 

Specify the file name as “CFX_CAV_On.cfx” and specify appropriate location and click Save.

 

1.2.13 Editing domain settings:

Double click on any one of the three domains i.e. InletExtension, Impeller or OutletExtension; or right mouse button on any of three domain names and click on Edit

Edit Domain

 

This will open details window for that Domain, select Fluid Pairs Model tab, use the following settings and click OK.

cav_on_Fluid_Pair

 

 

1.2.14 Saving Case File:

Go to: File > Save Case or click at the Save Case icon saveicon

 

 

1.2.15 Defining run and starting Solver:

Click at the Define Run icon defineRun

Specify the name and location of the definition file and click Save.

A new dialogue window will open; Select the solver input file and working directory location, this time we are initializing the solver with the converged results from the previous analysis from (Pump Cavitation Analysis in ANSYS CFX (Part I)).

Specify the following settings and click Start Run.

runsolver

 

 

 

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2 Responses so far.

  1. Texnap says:

    Hello, What exactly is meant with interphase transfer (mixture model and interphase length scale) and why did you turn it off? I dont really understand the section about it in the solver theory guide either. Can you explain it pls?

  2. admin says:

    Please refer to the ANSYS CFX-Solver Modeling Guide and search “Interphase Mass Transfer”

    “Interphase mass transfer occurs when mass is carried from one phase into another. It is applicable to both the inhomogeneous and homogeneous multiphase models. Some of the model libraries available in CFX-Pre contain simulation definitions for interface mass transfer cases, including boiling water and cavitation.

    Possible causes of interphase mass transfer are:
    • Change of thermodynamic phase. For example, melting/solidification in liquid-solid systems, evaporation/condensation in gas-liquid systems, and cavitation in gas-liquid systems.
    • Diffusion of a dissolved species across a phase boundary. This may or may not involve a change of phase of the dissolved species. Examples are gas dissolution, and evaporation of a liquid into a gas containing its vapor.
    • Breakup and coalescence may be treated as a mass transfer process between two phases representing different size groups of the same species.”

    For pump cavitation analysis we keep it turned off.

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