Thank you NickFL / Nikhil,

I need the heat to go on both directions. At the moment, I am not considering water flowing across the line heater, but later I may want to compare with the case where there is convection due to hotter water bouyancy in porous media.

I did a test by creating a line in DisgnModeler (representing one line heater):  1) added a New Sketch,  2) selected Line in Sketching tap and c) drew a line (see snapshot attached)

Then, I generated a Line from Sketches: Concept / Lines from Sketches

Next, I tried to imprint the line on a face/body by: Create / Body Operation. I selected "Imprint Faces" on Type, and tried to select the face and line, but it did not work. I got a error message saying:

Warning: Some selected bodies are invalid,

Line bodies are not permitted for boolean type operations. Context: Body Operation Feature BodyOp1

I did another test in which I created 3 Name Selection in Ansys Mesing using selected nodes (image below). However, these names do not appear in Boundary Conditions (Fluent).

Could you please guide me on how to imprint these 3 lines in DesignModeler? or can provide any other workaround to represent these three line heat sources in Fluent. Thanks in advance.