In ANSYS, one can define convection from a simple fluid-flow element (FLUID116) to solid or planar elements via thermal surface effect elements (SURF151 and SURF152). The face of the thermal surface effect element is ‘pasted’ on the solid or planar face while the ‘extra node’ is connected with the fluid thermal-pipe element. This allows for the bulk temperature in convection calculations to be based on a simplified representation of the fluid flow (i.e., bulk temperature is unknown and solved for).

In ANSYS 12.1, an additional option has been added to SURF152 where two extra nodes can be specified. This provides for more accurate calculations since the bulk temperature is no longer restricted to a single node of FLUID116 but determined from two nodes instead.

To connect the SURF152 elements to two nodes of FLUID116, use the new MSTOLE command. See Section 2.4.1 “Using the Surface-Effect Elements” in the Thermal Analysis Guide for more details. Also, it is worth noting that FLUID116 also includes new advection schemes as well.