BOUNDARY_THERMAL_BULKNODE

[francesca lugaresi]

Hi All, 

I'm trying to model convection within a rectangular closed cavity and have been trying to utilize the keyword *BOUNDARY_THERMAL_BULKNODE but without success. 

I defined a node at the center of my cavity (the bulk node) and defined a part PID with appropriate thermal properties TID.

The manual is not very clear and I think I might be misinterpreting some of the card's fields:

1. I don't really know what I am meant to type in the NBNSEG field the "number of element surface segments that transfer heat to this bulk node"? 
2. And also for the Nodal points (N1-N2-N3-N4) not sure which nodes are required here. 

Ideally, I would like to tranfer heat from all sides of the cavity, and to do so I would need to define either a SET_SEGMENT or a NODE_LIST to include all the elements (there are 30 solid elements on each cavity side). However, in the   *BOUNDARY_THERMAL_BULKNODE a SID or SSID cannot be defined. 

Can someone please explain how this keyword should be used or show me an example of a simulation that utilizes this keyword??

Thank you!

Francesa

[Arthur Shapiro]

I'm the original code developer of BOUNDARY_THERMAL_BULKNODE. I retired 6 years ago and don't know if the ability to define surface segments by a SET was added. That would be a very useful feature. Without that, the only thing I can suggest is to use LS-PrePost to define segment sets and then use a text editor to cut and paste the segment definitions from SET_SEGMENT to BOUNDARY_THERMAL_BULKNODE. See Chapter 10 slide 17 from https://www.dropbox.com/s/xef1q7l4cq4plvl/heat_transfer_class.pdf?dl=0 for details on BULKNODE. Here is a very simple input file https://www.dropbox.com/s/64ugwd1tjy3tufq/bulk1.k?dl=0

[francesca lugaresi]

Hi Arthur, 

I hadn't thought about this way of going around the problem. I have now used the bulknode keyword successfully. Thanks for your help!