Lattice structure heat exchanger simulation on CFX
 

I am simulating a heat exchanger with the core of a lattice structure, and it is a complicated geometry. Therefore I finely meshed it and got the total element numbers of 60M for hot and cold fluids.

I assigned the boundary conditions, including inlets, outlet and hot/cold interface, but I got the following error from the solver :

ERROR #001100279 has occurred in subroutine ErrAction.

Message: The zone group FLUID_ZG1 does not have enough vertices for partitioning in partitioning pass PASS1.

And also:

ERROR #001100279 has occurred in subroutine ErrAction.

Message: Stopped in routine PART_VERTEX_CPLD

I have tried the coarse mesh also, where the total number of elements was reduced to 30M and got the same error message.

I would appreciate it if you share your thoughts with me on this matter.

Many thanks