Learning Forum

[KIRANPETER]

Hi, I'm trying to create an actuator disc wind turbine using the momentum source term method without using the UDF. It wuld be great if anyone could help me to understand how to do this.

Thank You

[DrAmine]

Hi,

Do you have some more Information about your modeling strategy. You will need source terms that is why you will require UDF to prescribe your source terms. In case you can handle your problem with frozen rotor or transient sliding mesh ansatz there is no need for defining source terms.

 

A.

[KIRANPETER]

Hi,

I'm trying to model an actuator disc instead of an wind turbine in a rectangular domain and make the flow pass through this disk setting the x-momentum source term. But the flow is passing around the disk instead of go through it.

Thanks

Peter

[BainJT]

Hi KIRANPETER, 

I've been having the same issue. 

I am aiming to model a turbine in a control volume as an actuator disk. As I said, the issue I am having with my model is that the flow is passing around the disk, not through it as per the actuator disk theory.

I'm attempting to model it as a momentum sink, through a porous material. I expect this is achieved by setting the turbine/disk as a subdomain. An issue that I believe I may be facing is that the whole domain is being selected as the subdomain (only option available, is that because I used a subtract boolean in my geometry step?), but then this document suggests that you select the main domain is to be selected - https://www.sharcnet.ca/Software/Ansys/16.2.3/en-us/help/cfx_pre/i1309510.html 

Any help would be appreciated. If a further description of the problem is required, I will be happy to extend my explanation. 

 

Cheers, 

BainJT. 

[Rob]

If you've created a separate zone check you've shared topology otherwise the two zone may not know about each other and fluid cannot pass between them. 

[BainJT]

update: 

I have redrawn the geometry in Design Modeller (instead of importing from SolidWorks) and assigned the control volume and the disk as frozen - no boolean used. Meshed as required, made the disk a subdomain and assigned the momentum sink and it worked! 

Now my difficulty lies in analysing the force on the disk in CFD-Post, it doesn't appear as a location under function calculator. Does anyone have any suggestions on how I can overcome this? 

Newbie on the loose! 

Cheers, 

James. 

[Rob]

We'd noticed.....  

If you created the model in Fluent look for the "interior" surfaces. As it's not a wall there is no force, so you'll need to get creative. 

 

[MohamedAyman1]

Hi BainJt and all,

 

I have been trying to insert a momentum sink into the actuator but i failed.Could you please tell me how can i do it. I researched about this topic and i found that if we know the thrust coefficient of the Turbine, we could relate it to the axial momentum that it give to the incoming flow.Could someone help me ?.

thanks in advance!!