Learning Forum

[Shi Kun]

Hello,everyone. I have encountered some problems and wish to get your help.

1.I use the multiphase Eulerian-Eulerian model, and  i  want to use the  collisional dissipation of energy of ourselves. It can be loaded in Fluent by the form of UDF when partial differential equation of granular temperature Model is used, however, the source term of granular temperature disappear when select the algebraic formulation. I want to know if there exist an interface of collisional dissipation of energy when choice the algebraic formulation.

2.In the UDF, i want to get the gradient of granular temperature, how can i realize it in ansys2023.I have tried the way C_T_G and set in the TUI: solve->set->expert, but there have some trouble.

I really wish to get your reply and thank you in advance.

[Rob]

Use the default option for Granular Temperature, the PDE may not be suitable, but that then prevents sources of granular temperature. 

The command works if you don't adapt. Where did the mesh come from? 

[Shi Kun]

I am really appreciate for your reply. However, there are still some unclear places.

1.My task is to verify the term of collisional dissipation of energy (the source term of granular temperature) deduced by ourselves. In the start, I use the PDE of granular temperature Model, the interface of  granular temperature source can be found in Cell Zone Conditions（As shown in the picture）, but at this time, the calculation is always divergent. So I want to use the Phase property of granular temperature Model to have a try, however, the interface of  granular temperature source in Cell Zone Conditions disappear ,and then I don't know where should I add the collisional dissipation of energy (the source term of granular temperature) deduced by ourselves.

2.I need to set initial stacking area in adapt, maybe the mesh of here cause errors. It means if i set initial stacking area in adapt and then i won't get the gradient of granular temperature by the above method? Is there any other way to obtain the gradient of granular temperature？

[Rob]

The patch option only tends to cause problems if you patch a high volume fraction on/in a fluid jet OR the volume fraction is very near the packing limit. 

With your model I think you need to hook that directly into the Granular Temperature as you're replacing the Fluent model. 

[Shi Kun]

About the packing limit, I'm a little confused. when the number of Eulerian Phases set as 3 and there exist 2 granular phase. How should i give the packing limit of each phase in Fluent? It should be the value of single phase or the value after there mixing or a value  greater than 0.63？If the value of packing limit will influence the accuracy of model.

[Rob]

The limit is (I think) the sum of the granular phases. But, if you have two sizes then the smaller can fit into the gaps so you might want to increase the value, or start using a UDF to adjust things the limit based on volume fractions. 

https://ansyshelp.ansys.com/account/Secured?returnurl=/Views/Secured/corp/v231/en/flu_ug/flu_ug_sec_mphase_using_steps_eulerian.html%23flu_ug_sec_eulermp_using_phases

[Shi Kun]

Ok. Thanks for your suggestion. I've got it.