Flow simulation of two incompressible fluid streams

[Sidemountyucatan]

Dear all,

I have started to check out CFDOf WB (latest available version) and I have got a question to it. Is it possible to define two or more fluid properties in case of interfering fluid streams ? e.g. two incompressible liquids with different fluid properties get into contact and mix.

Thanks for your feedback.

Best Regards

Marcus

[oliveroxtoby]

Dear all,

I have started to check out CFDOf WB (latest available version) and I have got a question to it. Is it possible to define two or more fluid properties in case of interfering fluid streams ? e.g. two incompressible liquids with different fluid properties get into contact and mix.

Thanks for your feedback.

Best Regards

Marcus

You can simulate interacting fluid streams of imiscible substances (e.g. water, air, oil) using the interFoam or multiphaseInterFoam solvers. Miscible substances (that you would need, say, the multiphaseEulerFoam solver for) aren't supported as it stands.

[Sidemountyucatan]

Thx for your feedback ! Just to be sure: The functionality of simulating miscible substances is not
implemented in CFDOf yet, right ? I would have to deal with OPENFOAM directly.

In case of imiscible substances how can I setup the case in Freecad / CfdOf ? I mean, I couldn't
figure out where to choose the solver e.g. interFoam respectively how to define 2 different
fluids.

Do you some informations for me regarding those issues (example, tutorial, link to some other sources, etc.).

Thx a lot !

Best Regards

Marcus

[shIxx]

Thx for your feedback ! Just to be sure: The functionality of simulating miscible substances is not
implemented in CFDOf yet, right ? I would have to deal with OPENFOAM directly.

In case of imiscible substances how can I setup the case in Freecad / CfdOf ? I mean, I couldn't
figure out where to choose the solver e.g. interFoam respectively how to define 2 different
fluids.

Do you some informations for me regarding those issues (example, tutorial, link to some other sources, etc.).

Thx a lot !

Best Regards

Marcus

First you create a model of your entire fluid as one geometry (it could be a solid compound, if I understood that correctly) and then a second geometry (for example, a box) which will later be defined in the analysis as a "Initialization Zone". Now you have to start a transient simulation and select multiphase flow. then add two imiscible fluids (such as water and air) then create an initialization zone and define your box as one of the two fluids under volume fractions and set the value to 1 for 100%

see my attached example file

[Sidemountyucatan]

hi oliveroxtoby,.:
i donwloaded your example but there was the following error-message
0.0: Error writing case:
0.0: 'FeaturePython' object has no attribute 'CaseName'
0.0: Write case setup file failed

how can i fix that ?


Best regards

[Kunda1]

Please when asking for help please always add your Help About FreeCAD Copy to clipboard information (per the forum guidelines).

[oliveroxtoby]

hi oliveroxtoby,.:
i donwloaded your example but there was the following error-message
0.0: Error writing case:
0.0: 'FeaturePython' object has no attribute 'CaseName'
0.0: Write case setup file failed

how can i fix that ?


Best regards

There was a slight change in file format since @shlxx created that file. Here is an updated version.

[Sidemountyucatan]

hi olivertoxoby,

i have a question to a previous email of yours. You wrote (related to case of 2 immiscible fluids):

First you create a model of your entire fluid as one geometry (it could be a solid compound, if I understood that correctly) and then a second geometry (for example, a box) which will later be defined in the analysis as a "Initialization Zone". Now you have to start a transient simulation and select multiphase flow. then add two imiscible fluids (such as water and air) then create an initialization zone and define your box as one of the two fluids under volume fractions and set the value to 1 for 100%



I have a question especially to the Statement "create a model of your entire fluid as one geometry (it could be a solid compound, if I understood that correctly) and then a second geometry …". Does it mean that the entire geometry has to be done twice - one time for considering media 1 and one time just for media 2 - and superimpose them ? And meshed twice ?


Sorry, for the maybe stupid question but i do not really got the point.

Thx !

[oliveroxtoby]

hi olivertoxoby,

i have a question to a previous email of yours. You wrote (related to case of 2 immiscible fluids):

It wasn't me who wrote this reply - it was @shlxx.

First you create a model of your entire fluid as one geometry (it could be a solid compound, if I understood that correctly) and then a second geometry (for example, a box) which will later be defined in the analysis as a "Initialization Zone". Now you have to start a transient simulation and select multiphase flow. then add two imiscible fluids (such as water and air) then create an initialization zone and define your box as one of the two fluids under volume fractions and set the value to 1 for 100%



I have a question especially to the Statement "create a model of your entire fluid as one geometry (it could be a solid compound, if I understood that correctly) and then a second geometry …". Does it mean that the entire geometry has to be done twice - one time for considering media 1 and one time just for media 2 - and superimpose them ? And meshed twice ?

No, you only create one mesh. There is one geometry for the simulation. However, you have the option to initialise the volume fraction field to a certain value in a certain area if you wish to start with a particular initial distribution of the fluids. You do this with (one or more) initialisation zone(s).