[abhinavkolla89]

I am creating two annular cylinders...the inner radius of the outer cylinder being equal to the outer radius of the inner cylinder...
inner cylinder dimensions,r1 = 0.2 , r2 = 0.5
outer cylinder dimensions,r3 = 0.5 , r4 = 0.8

now i want them to be in thermal contact but do not wish to merge/unite them as they are of seperate material i.e i want them to be as seperate volumes and be in contact for heat flow...when i created them by just using the radiuses specified and doing the boolean operations to generate the annular cylinders and simulated them in fluent (energy equation involved)...the temp profile is as shown.....which clearly indicates they are not in contact.

plz help

[-mAx-]

yep your disk aren't connected, so the solver understand there are walls between your disks (check the BL, I am pretty sure you will see walls between annular cylinders)
So you need to do some splits:
Create a disk with r=0.8
Create a circle with r= 0.2
Split the disk with the r=0.2 circle, and delete the r=0.2 disk which has been created
You have now a disk with r=0.2 hollowed disk
Now create a circle with r=0.5, and split the previous disk with this r=0.5 circle.
That's it: you have to distinct connected disks, on which you may apply different set-up