User Routine, Schiller Naumann

Mohamed Abohelwa · November 12, 2021, 06:00

Hi,

I want to modify the equation of the (Schiller Naumann) drag model to include some terms and make it valid for nonspherical particles. Is there anyway to do that without using Fortran and User Routines ?
If no, are there any tutorials explaining how to use User Routines ?

ghorrocks · November 14, 2021, 16:55

Set the Drag Force to "Particle Transport Drag Coefficient" and then you can define your own function for the drag coefficient. You can define this drag function by user fortran or CEL.

Mohamed Abohelwa · November 15, 2021, 03:09

Hi Glenn,

When I did that, I got this error:
( Parameter 'Drag Coefficient' in object '/FLOW:Flow Analysis 1/DOMAIN:Inlet_Rotor_Outlet_Grob/FLUID PAIR:Fluid 1 | Kalkpartikel/MOMENTUM TRANSFER/DRAG FORCE/DRAG COEFFICIENT' is not allowed to be assigned an expression value that depends on variables. It must be assigned a numeric value, or an expression that resolves to a constant value.)

While I don't want to set the drag coefficient as a constant value but it should be variable depending on other parameters such as the Reynolds number which is not constant in the whole domain but it varies also depending on the flow and particle velocities.

ghorrocks · November 15, 2021, 03:14

That is disappointing. Limiting it to constant variables is very unfortunate.

Oh well, then your only option is the existing models or user fortran.

Mohamed Abohelwa · November 15, 2021, 03:22

Do you know any tutorials for using User Fortran ?

I have read the CFX documentation, but it is not clear to me how to compile the (.F) file for CFX.

ghorrocks · November 15, 2021, 03:32

You need to make sure you have the supported compiler for your version of CFX. The documentation covers all that and a few simple tutorial examples.

November 12, 2021, 06:00	User Routine, Schiller Naumann	#1
Mohamed Abohelwa New Member Join Date: Sep 2019 Posts: 14 Rep Power: 6	Hi, I want to modify the equation of the (Schiller Naumann) drag model to include some terms and make it valid for nonspherical particles. Is there anyway to do that without using Fortran and User Routines ? If no, are there any tutorials explaining how to use User Routines ?

November 14, 2021, 16:55		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,729 Rep Power: 143	Set the Drag Force to "Particle Transport Drag Coefficient" and then you can define your own function for the drag coefficient. You can define this drag function by user fortran or CEL. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

November 15, 2021, 03:14		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,729 Rep Power: 143	That is disappointing. Limiting it to constant variables is very unfortunate. Oh well, then your only option is the existing models or user fortran. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

November 15, 2021, 03:32		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,729 Rep Power: 143	You need to make sure you have the supported compiler for your version of CFX. The documentation covers all that and a few simple tutorial examples. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

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November 15, 2021, 03:09		#3
Mohamed Abohelwa New Member Join Date: Sep 2019 Posts: 14 Rep Power: 6	Hi Glenn, When I did that, I got this error: ( Parameter 'Drag Coefficient' in object '/FLOW:Flow Analysis 1/DOMAIN:Inlet_Rotor_Outlet_Grob/FLUID PAIR:Fluid 1 \| Kalkpartikel/MOMENTUM TRANSFER/DRAG FORCE/DRAG COEFFICIENT' is not allowed to be assigned an expression value that depends on variables. It must be assigned a numeric value, or an expression that resolves to a constant value.) While I don't want to set the drag coefficient as a constant value but it should be variable depending on other parameters such as the Reynolds number which is not constant in the whole domain but it varies also depending on the flow and particle velocities.

November 15, 2021, 03:22		#5
Mohamed Abohelwa New Member Join Date: Sep 2019 Posts: 14 Rep Power: 6	Do you know any tutorials for using User Fortran ? I have read the CFX documentation, but it is not clear to me how to compile the (.F) file for CFX.