Learning Forum

[Mohammad]

Hello, 

I hope you are well. I want to run a one-way coupled DPM simulation by first solving the continuous phase and then solving for the dispersed particles using an unsteady simulation. Is it possible in FLUENT to map the sum of the particle volume fraction and the sum of the particle volume at each cell and use these variables as a part of a field function/expression? 

Kind regards,

Mohammad

[Rob]

To an extent yes. Are you looking at steady flow and transient particles or transient flow and particles? Have a look in the contour plots for what's available, and check the definitions in the Field Function list as not all are obvious. 

You may also want to read up on Custom Field Functions and Expressions. If you're exporting data I'd favour the former as I can't remember quite where we're at with using expressions for that. 

[Mohammad]

Hi Rob, 

Thank you for your reply. I am looking at steady flow and transient particles. I want to 'map' the volume fraction and other particle variables onto the same mesh used for the continious phase for every time step, which then these variables are made available for use in custom field functions and can view in contours etc.

 

Kind regards,

Mohammad

[Rob]

The particle positions are updated with each particle step, so if you stop the calculation you can see the current data. The data averaging might also be useful. 

Be VERY careful with the contour plots with DPM. Read the exact definitions before drawing any conclusions. 

[Mohammad]

Thank you for your response. The contour plots only displays the particle variables (e.g volume fraction of particles to air) for the particles in the Lagrangian frame i.e you can only see the particles which are coloured by what DPM variable you select in the field function. However, I want to map these DPM variables (e.g volume fraction) onto the volume mesh (Eulerian frame). 

 

Kind regards, 

Mohammad

[Rob]

The contours do show the data mapped onto the Euler mesh - the DPM tracks are potentially the Euler values mapped onto the particles. 

[G if]

Maybe you can use the udf to finish it.I recenty use the DEFINE_DPM_SOURCE,it's able to track every cell and particles in cell,and you can read their character.I hope it's useful for you.

[Mohammad]

Hi Rob, 

From what I understood from your inputs as well as reading the user guide:

1. As long as I am using unsteady particle tracking and select data sampling for time statistics in the run calculation task page,  then I am able to select Mean values under contour plots for DPM variables in the DPM dialog box without having to select interaction with continious phase.

2. If I am not using unsteady particle tracking then I must select interaction with continious phase in order for the mean dpm variables to be mapped to the Eulerian mesh.

3. Regardless, since the mean values are now mapped to the mesh, these dpm variables are available to use in expressions?

Is this correct? 

 

Many thanks

 

 

[G if]

I don't know what your field function is , but DEFINE_DPM_SOURCE is acturally powerful.It's a way to get every particle messages in a cell and you can edit both this cell and particles in cell.Maybe you can make your flied function transform to it, or you program a field function udf,which can get the information.But I have never tried it.If you want to use DEFINE_DPM_SOURCE,you can read the ansys fluent's udf document.

Note:It's a huge work about learning.

[Mohammad]

Hi G if, 

 

Thanks for your input. Please can you provide more information and context on how you used it? Thank you!

[Rob]

Try the various transient/coupled options. For steady you only need one DPM update with coupled active to fill the field variables - assuming the coupling is weak.